diff --git a/src/chromium/ExecutionContext.ts b/src/chromium/ExecutionContext.ts
index b719a15b92..683d0ca56c 100644
--- a/src/chromium/ExecutionContext.ts
+++ b/src/chromium/ExecutionContext.ts
@@ -18,7 +18,6 @@
 import { CDPSession } from './Connection';
 import { helper } from '../helper';
 import { valueFromRemoteObject, getExceptionMessage, releaseObject } from './protocolHelper';
-import { createJSHandle } from './JSHandle';
 import { Protocol } from './protocol';
 import * as js from '../javascript';
 import * as dom from '../dom';
@@ -51,7 +50,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
       }).catch(rewriteError);
       if (exceptionDetails)
         throw new Error('Evaluation failed: ' + getExceptionMessage(exceptionDetails));
-      return returnByValue ? valueFromRemoteObject(remoteObject) : createJSHandle(context, remoteObject);
+      return returnByValue ? valueFromRemoteObject(remoteObject) : toHandle(context, remoteObject);
     }
 
     if (typeof pageFunction !== 'function')
@@ -92,7 +91,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
     const { exceptionDetails, result: remoteObject } = await callFunctionOnPromise.catch(rewriteError);
     if (exceptionDetails)
       throw new Error('Evaluation failed: ' + getExceptionMessage(exceptionDetails));
-    return returnByValue ? valueFromRemoteObject(remoteObject) : createJSHandle(context, remoteObject);
+    return returnByValue ? valueFromRemoteObject(remoteObject) : toHandle(context, remoteObject);
 
     function convertArgument(arg: any): any {
       if (typeof arg === 'bigint') // eslint-disable-line valid-typeof
@@ -133,14 +132,6 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
     }
   }
 
-  async adoptBackendNodeId(context: js.ExecutionContext, backendNodeId: Protocol.DOM.BackendNodeId) {
-    const {object} = await this._client.send('DOM.resolveNode', {
-      backendNodeId,
-      executionContextId: this._contextId,
-    });
-    return createJSHandle(context, object) as dom.ElementHandle;
-  }
-
   async getProperties(handle: js.JSHandle): Promise<Map<string, js.JSHandle>> {
     const response = await this._client.send('Runtime.getProperties', {
       objectId: toRemoteObject(handle).objectId,
@@ -150,7 +141,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
     for (const property of response.result) {
       if (!property.enumerable)
         continue;
-      result.set(property.name, createJSHandle(handle.executionContext(), property.value));
+      result.set(property.name, toHandle(handle.executionContext(), property.value));
     }
     return result;
   }
@@ -189,6 +180,13 @@ export function toRemoteObject(handle: js.JSHandle): Protocol.Runtime.RemoteObje
   return (handle as any)[remoteObjectSymbol];
 }
 
-export function markJSHandle(handle: js.JSHandle, remoteObject: Protocol.Runtime.RemoteObject) {
+export function toHandle(context: js.ExecutionContext, remoteObject: Protocol.Runtime.RemoteObject): js.JSHandle {
+  if (remoteObject.subtype === 'node' && context.frame()) {
+    const handle = new dom.ElementHandle(context);
+    (handle as any)[remoteObjectSymbol] = remoteObject;
+    return handle;
+  }
+  const handle = new js.JSHandle(context);
   (handle as any)[remoteObjectSymbol] = remoteObject;
+  return handle;
 }
diff --git a/src/chromium/FrameManager.ts b/src/chromium/FrameManager.ts
index 208f94de60..f131c50683 100644
--- a/src/chromium/FrameManager.ts
+++ b/src/chromium/FrameManager.ts
@@ -16,14 +16,15 @@
  */
 
 import { EventEmitter } from 'events';
+import * as dom from '../dom';
 import * as frames from '../frames';
 import { assert, debugError } from '../helper';
 import * as js from '../javascript';
-import * as dom from '../dom';
 import * as network from '../network';
 import { TimeoutSettings } from '../TimeoutSettings';
 import { CDPSession } from './Connection';
-import { EVALUATION_SCRIPT_URL, ExecutionContextDelegate, toRemoteObject } from './ExecutionContext';
+import { EVALUATION_SCRIPT_URL, ExecutionContextDelegate } from './ExecutionContext';
+import { DOMWorldDelegate } from './JSHandle';
 import { LifecycleWatcher } from './LifecycleWatcher';
 import { NetworkManager } from './NetworkManager';
 import { Page } from './Page';
@@ -178,13 +179,6 @@ export class FrameManager extends EventEmitter implements frames.FrameDelegate {
       throw error;
   }
 
-  async adoptElementHandle(elementHandle: dom.ElementHandle, context: js.ExecutionContext): Promise<dom.ElementHandle> {
-    const nodeInfo = await this._client.send('DOM.describeNode', {
-      objectId: toRemoteObject(elementHandle).objectId,
-    });
-    return (context._delegate as ExecutionContextDelegate).adoptBackendNodeId(context, nodeInfo.node.backendNodeId);
-  }
-
   _onLifecycleEvent(event: Protocol.Page.lifecycleEventPayload) {
     const frame = this._frames.get(event.frameId);
     if (!frame)
@@ -324,7 +318,9 @@ export class FrameManager extends EventEmitter implements frames.FrameDelegate {
     const frame = this._frames.get(frameId) || null;
     if (contextPayload.auxData && contextPayload.auxData['type'] === 'isolated')
       this._isolatedWorlds.add(contextPayload.name);
-    const context: js.ExecutionContext = new js.ExecutionContext(new ExecutionContextDelegate(this._client, contextPayload), frame);
+    const context = new js.ExecutionContext(new ExecutionContextDelegate(this._client, contextPayload));
+    if (frame)
+      context._domWorld = new dom.DOMWorld(context, new DOMWorldDelegate(this, frame));
     if (frame) {
       if (contextPayload.auxData && !!contextPayload.auxData['isDefault'])
         frame._contextCreated('main', context);
diff --git a/src/chromium/JSHandle.ts b/src/chromium/JSHandle.ts
index 1c27dcb3de..18212c70ef 100644
--- a/src/chromium/JSHandle.ts
+++ b/src/chromium/JSHandle.ts
@@ -16,7 +16,6 @@
  */
 
 import { assert, debugError } from '../helper';
-import * as js from '../javascript';
 import * as dom from '../dom';
 import * as input from '../input';
 import * as types from '../types';
@@ -24,29 +23,20 @@ import * as frames from '../frames';
 import { CDPSession } from './Connection';
 import { FrameManager } from './FrameManager';
 import { Protocol } from './protocol';
-import { ExecutionContextDelegate, markJSHandle, toRemoteObject } from './ExecutionContext';
+import { toRemoteObject, toHandle, ExecutionContextDelegate } from './ExecutionContext';
 
-export function createJSHandle(context: js.ExecutionContext, remoteObject: Protocol.Runtime.RemoteObject): js.JSHandle {
-  const frame = context.frame();
-  if (remoteObject.subtype === 'node' && frame) {
-    const frameManager = frame._delegate as FrameManager;
-    const page = frameManager.page();
-    const delegate = new DOMWorldDelegate((context._delegate as ExecutionContextDelegate)._client, frameManager);
-    const handle = new dom.ElementHandle(context, page.keyboard, page.mouse, delegate);
-    markJSHandle(handle, remoteObject);
-    return handle;
-  }
-  const handle = new js.JSHandle(context);
-  markJSHandle(handle, remoteObject);
-  return handle;
-}
-
-class DOMWorldDelegate implements dom.DOMWorldDelegate {
+export class DOMWorldDelegate implements dom.DOMWorldDelegate {
+  readonly keyboard: input.Keyboard;
+  readonly mouse: input.Mouse;
+  readonly frame: frames.Frame;
   private _client: CDPSession;
   private _frameManager: FrameManager;
 
-  constructor(client: CDPSession, frameManager: FrameManager) {
-    this._client = client;
+  constructor(frameManager: FrameManager, frame: frames.Frame) {
+    this.keyboard = frameManager.page().keyboard;
+    this.mouse = frameManager.page().mouse;
+    this.frame = frame;
+    this._client = frameManager._client;
     this._frameManager = frameManager;
   }
 
@@ -183,8 +173,8 @@ class DOMWorldDelegate implements dom.DOMWorldDelegate {
     // Filter out quads that have too small area to click into.
     const { clientWidth, clientHeight } = layoutMetrics.layoutViewport;
     const quads = result.quads.map(fromProtocolQuad)
-      .map(quad => intersectQuadWithViewport(quad, clientWidth, clientHeight))
-      .filter(quad => computeQuadArea(quad) > 1);
+        .map(quad => intersectQuadWithViewport(quad, clientWidth, clientHeight))
+        .filter(quad => computeQuadArea(quad) > 1);
     if (!quads.length)
       throw new Error('Node is either not visible or not an HTMLElement');
     // Return the middle point of the first quad.
@@ -234,4 +224,19 @@ class DOMWorldDelegate implements dom.DOMWorldDelegate {
   async setInputFiles(handle: dom.ElementHandle, files: input.FilePayload[]): Promise<void> {
     await handle.evaluate(input.setFileInputFunction, files);
   }
+
+  async adoptElementHandle(handle: dom.ElementHandle, to: dom.DOMWorld): Promise<dom.ElementHandle> {
+    const nodeInfo = await this._client.send('DOM.describeNode', {
+      objectId: toRemoteObject(handle).objectId,
+    });
+    return this.adoptBackendNodeId(nodeInfo.node.backendNodeId, to);
+  }
+
+  async adoptBackendNodeId(backendNodeId: Protocol.DOM.BackendNodeId, to: dom.DOMWorld): Promise<dom.ElementHandle> {
+    const {object} = await this._client.send('DOM.resolveNode', {
+      backendNodeId,
+      executionContextId: (to.context._delegate as ExecutionContextDelegate)._contextId,
+    });
+    return toHandle(to.context, object).asElement()!;
+  }
 }
diff --git a/src/chromium/Page.ts b/src/chromium/Page.ts
index 7ce6e52e88..3dd1545e7c 100644
--- a/src/chromium/Page.ts
+++ b/src/chromium/Page.ts
@@ -35,8 +35,7 @@ import { PDF } from './features/pdf';
 import { Workers } from './features/workers';
 import { FrameManager, FrameManagerEvents } from './FrameManager';
 import { RawMouseImpl, RawKeyboardImpl } from './Input';
-import { createJSHandle } from './JSHandle';
-import { toRemoteObject } from './ExecutionContext';
+import { toHandle, toRemoteObject } from './ExecutionContext';
 import { NetworkManagerEvents } from './NetworkManager';
 import { Protocol } from './protocol';
 import { getExceptionMessage, releaseObject, valueFromRemoteObject } from './protocolHelper';
@@ -48,7 +47,7 @@ import * as dom from '../dom';
 import * as frames from '../frames';
 import * as js from '../javascript';
 import * as network from '../network';
-import { ExecutionContextDelegate } from './ExecutionContext';
+import { DOMWorldDelegate } from './JSHandle';
 
 const writeFileAsync = helper.promisify(fs.writeFile);
 
@@ -159,8 +158,8 @@ export class Page extends EventEmitter {
     if (!this._fileChooserInterceptors.size)
       return;
     const frame = this._frameManager.frame(event.frameId);
-    const context = await frame._utilityContext();
-    const handle = await (context._delegate as ExecutionContextDelegate).adoptBackendNodeId(context, event.backendNodeId);
+    const utilityWorld = await frame._utilityDOMWorld();
+    const handle = await (utilityWorld.delegate as DOMWorldDelegate).adoptBackendNodeId(event.backendNodeId, utilityWorld);
     const interceptors = Array.from(this._fileChooserInterceptors);
     this._fileChooserInterceptors.clear();
     const multiple = await handle.evaluate((element: HTMLInputElement) => !!element.multiple);
@@ -321,7 +320,7 @@ export class Page extends EventEmitter {
       return;
     }
     const context = this._frameManager.executionContextById(event.executionContextId);
-    const values = event.args.map(arg => createJSHandle(context, arg));
+    const values = event.args.map(arg => toHandle(context, arg));
     this._addConsoleMessage(event.type, values, event.stackTrace);
   }
 
diff --git a/src/chromium/features/workers.ts b/src/chromium/features/workers.ts
index 93409b3a78..ecdf1ba046 100644
--- a/src/chromium/features/workers.ts
+++ b/src/chromium/features/workers.ts
@@ -21,8 +21,7 @@ import { Protocol } from '../protocol';
 import { Events } from '../events';
 import * as types from '../../types';
 import * as js from '../../javascript';
-import { ExecutionContextDelegate } from '../ExecutionContext';
-import { createJSHandle } from '../JSHandle';
+import { toHandle, ExecutionContextDelegate } from '../ExecutionContext';
 
 type AddToConsoleCallback = (type: string, args: js.JSHandle[], stackTrace: Protocol.Runtime.StackTrace | undefined) => void;
 type HandleExceptionCallback = (exceptionDetails: Protocol.Runtime.ExceptionDetails) => void;
@@ -68,8 +67,8 @@ export class Worker extends EventEmitter {
     this._executionContextPromise = new Promise(x => this._executionContextCallback = x);
     let jsHandleFactory: (o: Protocol.Runtime.RemoteObject) => js.JSHandle;
     this._client.once('Runtime.executionContextCreated', async event => {
-      jsHandleFactory = remoteObject => createJSHandle(executionContext, remoteObject);
-      const executionContext = new js.ExecutionContext(new ExecutionContextDelegate(client, event.context), null);
+      jsHandleFactory = remoteObject => toHandle(executionContext, remoteObject);
+      const executionContext = new js.ExecutionContext(new ExecutionContextDelegate(client, event.context));
       this._executionContextCallback(executionContext);
     });
     // This might fail if the target is closed before we recieve all execution contexts.
diff --git a/src/dom.ts b/src/dom.ts
index 9a67ef218c..a140bd8e77 100644
--- a/src/dom.ts
+++ b/src/dom.ts
@@ -7,28 +7,73 @@ import Injected from './injected/injected';
 import * as input from './input';
 import * as js from './javascript';
 import * as types from './types';
+import * as injectedSource from './generated/injectedSource';
+import * as cssSelectorEngineSource from './generated/cssSelectorEngineSource';
+import * as xpathSelectorEngineSource from './generated/xpathSelectorEngineSource';
 
 type SelectorRoot = Element | ShadowRoot | Document;
 
 export interface DOMWorldDelegate {
+  keyboard: input.Keyboard;
+  mouse: input.Mouse;
+  frame: frames.Frame;
   isJavascriptEnabled(): boolean;
   contentFrame(handle: ElementHandle): Promise<frames.Frame | null>;
   boundingBox(handle: ElementHandle): Promise<types.Rect | null>;
   screenshot(handle: ElementHandle, options?: any): Promise<string | Buffer>;
   ensurePointerActionPoint(handle: ElementHandle, relativePoint?: types.Point): Promise<types.Point>;
   setInputFiles(handle: ElementHandle, files: input.FilePayload[]): Promise<void>;
+  adoptElementHandle(handle: ElementHandle, to: DOMWorld): Promise<ElementHandle>;
+}
+
+export class DOMWorld {
+  readonly context: js.ExecutionContext;
+  readonly delegate: DOMWorldDelegate;
+
+  private _injectedPromise?: Promise<js.JSHandle>;
+  private _documentPromise?: Promise<ElementHandle>;
+
+  constructor(context: js.ExecutionContext, delegate: DOMWorldDelegate) {
+    this.context = context;
+    this.delegate = delegate;
+  }
+
+  injected(): Promise<js.JSHandle> {
+    if (!this._injectedPromise) {
+      const engineSources = [cssSelectorEngineSource.source, xpathSelectorEngineSource.source];
+      const source = `
+        new (${injectedSource.source})([
+          ${engineSources.join(',\n')}
+        ])
+      `;
+      this._injectedPromise = this.context.evaluateHandle(source);
+    }
+    return this._injectedPromise;
+  }
+
+  _document(): Promise<ElementHandle> {
+    if (!this._documentPromise)
+      this._documentPromise = this.context.evaluateHandle('document').then(handle => handle.asElement()!);
+    return this._documentPromise;
+  }
+
+  async adoptElementHandle(handle: ElementHandle, dispose: boolean): Promise<ElementHandle> {
+    if (handle.executionContext() === this.context)
+      return handle;
+    const adopted = this.delegate.adoptElementHandle(handle, this);
+    if (dispose)
+      await handle.dispose();
+    return adopted;
+  }
 }
 
 export class ElementHandle extends js.JSHandle {
-  private _delegate: DOMWorldDelegate;
-  private _keyboard: input.Keyboard;
-  private _mouse: input.Mouse;
+  private readonly _world: DOMWorld;
 
-  constructor(context: js.ExecutionContext, keyboard: input.Keyboard, mouse: input.Mouse, delegate: DOMWorldDelegate) {
+  constructor(context: js.ExecutionContext) {
     super(context);
-    this._delegate = delegate;
-    this._keyboard = keyboard;
-    this._mouse = mouse;
+    assert(context._domWorld, 'Element handle should have a dom world');
+    this._world = context._domWorld;
   }
 
   asElement(): ElementHandle | null {
@@ -36,7 +81,7 @@ export class ElementHandle extends js.JSHandle {
   }
 
   async contentFrame(): Promise<frames.Frame | null> {
-    return this._delegate.contentFrame(this);
+    return this._world.delegate.contentFrame(this);
   }
 
   async _scrollIntoViewIfNeeded() {
@@ -63,35 +108,35 @@ export class ElementHandle extends js.JSHandle {
       if (visibleRatio !== 1.0)
         element.scrollIntoView({block: 'center', inline: 'center', behavior: 'instant'});
       return false;
-    }, this._delegate.isJavascriptEnabled());
+    }, this._world.delegate.isJavascriptEnabled());
     if (error)
       throw new Error(error);
   }
 
   async _performPointerAction(action: (point: types.Point) => Promise<void>, options?: input.PointerActionOptions): Promise<void> {
-    const point = await this._delegate.ensurePointerActionPoint(this, options ? options.relativePoint : undefined);
+    const point = await this._world.delegate.ensurePointerActionPoint(this, options ? options.relativePoint : undefined);
     let restoreModifiers: input.Modifier[] | undefined;
     if (options && options.modifiers)
-      restoreModifiers = await this._keyboard._ensureModifiers(options.modifiers);
+      restoreModifiers = await this._world.delegate.keyboard._ensureModifiers(options.modifiers);
     await action(point);
     if (restoreModifiers)
-      await this._keyboard._ensureModifiers(restoreModifiers);
+      await this._world.delegate.keyboard._ensureModifiers(restoreModifiers);
   }
 
   hover(options?: input.PointerActionOptions): Promise<void> {
-    return this._performPointerAction(point => this._mouse.move(point.x, point.y), options);
+    return this._performPointerAction(point => this._world.delegate.mouse.move(point.x, point.y), options);
   }
 
   click(options?: input.ClickOptions): Promise<void> {
-    return this._performPointerAction(point => this._mouse.click(point.x, point.y, options), options);
+    return this._performPointerAction(point => this._world.delegate.mouse.click(point.x, point.y, options), options);
   }
 
   dblclick(options?: input.MultiClickOptions): Promise<void> {
-    return this._performPointerAction(point => this._mouse.dblclick(point.x, point.y, options), options);
+    return this._performPointerAction(point => this._world.delegate.mouse.dblclick(point.x, point.y, options), options);
   }
 
   tripleclick(options?: input.MultiClickOptions): Promise<void> {
-    return this._performPointerAction(point => this._mouse.tripleclick(point.x, point.y, options), options);
+    return this._performPointerAction(point => this._world.delegate.mouse.tripleclick(point.x, point.y, options), options);
   }
 
   async select(...values: (string | ElementHandle | input.SelectOption)[]): Promise<string[]> {
@@ -115,13 +160,13 @@ export class ElementHandle extends js.JSHandle {
     if (error)
       throw new Error(error);
     await this.focus();
-    await this._keyboard.sendCharacters(value);
+    await this._world.delegate.keyboard.sendCharacters(value);
   }
 
   async setInputFiles(...files: (string|input.FilePayload)[]) {
     const multiple = await this.evaluate((element: HTMLInputElement) => !!element.multiple);
     assert(multiple || files.length <= 1, 'Non-multiple file input can only accept single file!');
-    await this._delegate.setInputFiles(this, await input.loadFiles(files));
+    await this._world.delegate.setInputFiles(this, await input.loadFiles(files));
   }
 
   async focus() {
@@ -130,26 +175,26 @@ export class ElementHandle extends js.JSHandle {
 
   async type(text: string, options: { delay: (number | undefined); } | undefined) {
     await this.focus();
-    await this._keyboard.type(text, options);
+    await this._world.delegate.keyboard.type(text, options);
   }
 
   async press(key: string, options: { delay?: number; text?: string; } | undefined) {
     await this.focus();
-    await this._keyboard.press(key, options);
+    await this._world.delegate.keyboard.press(key, options);
   }
 
   async boundingBox(): Promise<types.Rect | null> {
-    return this._delegate.boundingBox(this);
+    return this._world.delegate.boundingBox(this);
   }
 
   async screenshot(options: any = {}): Promise<string | Buffer> {
-    return this._delegate.screenshot(this, options);
+    return this._world.delegate.screenshot(this, options);
   }
 
   async $(selector: string): Promise<ElementHandle | null> {
     const handle = await this.evaluateHandle(
         (root: SelectorRoot, selector: string, injected: Injected) => injected.querySelector('css=' + selector, root),
-        selector, await this._context._injected()
+        selector, await this._world.injected()
     );
     const element = handle.asElement();
     if (element)
@@ -161,7 +206,7 @@ export class ElementHandle extends js.JSHandle {
   async $$(selector: string): Promise<ElementHandle[]> {
     const arrayHandle = await this.evaluateHandle(
         (root: SelectorRoot, selector: string, injected: Injected) => injected.querySelectorAll('css=' + selector, root),
-        selector, await this._context._injected()
+        selector, await this._world.injected()
     );
     const properties = await arrayHandle.getProperties();
     await arrayHandle.dispose();
@@ -186,7 +231,7 @@ export class ElementHandle extends js.JSHandle {
   $$eval: types.$$Eval = async (selector, pageFunction, ...args) => {
     const arrayHandle = await this.evaluateHandle(
         (root: SelectorRoot, selector: string, injected: Injected) => injected.querySelectorAll('css=' + selector, root),
-        selector, await this._context._injected()
+        selector, await this._world.injected()
     );
 
     const result = await arrayHandle.evaluate(pageFunction, ...args as any);
@@ -197,7 +242,7 @@ export class ElementHandle extends js.JSHandle {
   async $x(expression: string): Promise<ElementHandle[]> {
     const arrayHandle = await this.evaluateHandle(
         (root: SelectorRoot, expression: string, injected: Injected) => injected.querySelectorAll('xpath=' + expression, root),
-        expression, await this._context._injected()
+        expression, await this._world.injected()
     );
     const properties = await arrayHandle.getProperties();
     await arrayHandle.dispose();
diff --git a/src/firefox/ExecutionContext.ts b/src/firefox/ExecutionContext.ts
index f67e6d32db..0dff1c6497 100644
--- a/src/firefox/ExecutionContext.ts
+++ b/src/firefox/ExecutionContext.ts
@@ -16,8 +16,8 @@
  */
 
 import {helper, debugError} from '../helper';
-import { createHandle } from './JSHandle';
 import * as js from '../javascript';
+import * as dom from '../dom';
 import { JugglerSession } from './Connection';
 
 export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
@@ -48,7 +48,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
         expression: pageFunction.trim(),
         executionContextId: this._executionContextId,
       }).catch(rewriteError);
-      return createHandle(context, payload.result, payload.exceptionDetails);
+      return toHandle(context, payload.result, payload.exceptionDetails);
     }
     if (typeof pageFunction !== 'function')
       throw new Error(`Expected to get |string| or |function| as the first argument, but got "${pageFunction}" instead.`);
@@ -101,7 +101,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
       throw err;
     }
     const payload = await callFunctionPromise.catch(rewriteError);
-    return createHandle(context, payload.result, payload.exceptionDetails);
+    return toHandle(context, payload.result, payload.exceptionDetails);
 
     function rewriteError(error) {
       if (error.message.includes('Failed to find execution context with id'))
@@ -117,7 +117,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
     });
     const result = new Map();
     for (const property of response.properties)
-      result.set(property.name, createHandle(handle.executionContext(), property.value, null));
+      result.set(property.name, toHandle(handle.executionContext(), property.value, null));
     return result;
   }
 
@@ -163,8 +163,21 @@ export function toPayload(handle: js.JSHandle): any {
   return (handle as any)[payloadSymbol];
 }
 
-export function markJSHandle(handle: js.JSHandle, payload: any) {
-  (handle as any)[payloadSymbol] = payload;
+export function toHandle(context: js.ExecutionContext, result: any, exceptionDetails?: any) {
+  if (exceptionDetails) {
+    if (exceptionDetails.value)
+      throw new Error('Evaluation failed: ' + JSON.stringify(exceptionDetails.value));
+    else
+      throw new Error('Evaluation failed: ' + exceptionDetails.text + '\n' + exceptionDetails.stack);
+  }
+  if (result.subtype === 'node') {
+    const handle = new dom.ElementHandle(context);
+    (handle as any)[payloadSymbol] = result;
+    return handle;
+  }
+  const handle = new js.JSHandle(context);
+  (handle as any)[payloadSymbol] = result;
+  return handle;
 }
 
 export function deserializeValue({unserializableValue, value}) {
diff --git a/src/firefox/FrameManager.ts b/src/firefox/FrameManager.ts
index 51ac44cfc3..142a1b8727 100644
--- a/src/firefox/FrameManager.ts
+++ b/src/firefox/FrameManager.ts
@@ -27,6 +27,7 @@ import { ExecutionContextDelegate } from './ExecutionContext';
 import { NavigationWatchdog, NextNavigationWatchdog } from './NavigationWatchdog';
 import { Page } from './Page';
 import { NetworkManager } from './NetworkManager';
+import { DOMWorldDelegate } from './JSHandle';
 
 export const FrameManagerEvents = {
   FrameNavigated: Symbol('FrameManagerEvents.FrameNavigated'),
@@ -80,8 +81,9 @@ export class FrameManager extends EventEmitter implements frames.FrameDelegate {
   _onExecutionContextCreated({executionContextId, auxData}) {
     const frameId = auxData ? auxData.frameId : null;
     const frame = this._frames.get(frameId) || null;
-    const context = new js.ExecutionContext(new ExecutionContextDelegate(this._session, executionContextId), frame);
+    const context = new js.ExecutionContext(new ExecutionContextDelegate(this._session, executionContextId));
     if (frame) {
+      context._domWorld = new dom.DOMWorld(context, new DOMWorldDelegate(this, frame));
       frame._contextCreated('main', context);
       frame._contextCreated('utility', context);
     }
@@ -175,11 +177,6 @@ export class FrameManager extends EventEmitter implements frames.FrameDelegate {
     helper.removeEventListeners(this._eventListeners);
   }
 
-  async adoptElementHandle(elementHandle: dom.ElementHandle, context: js.ExecutionContext): Promise<dom.ElementHandle> {
-    assert(false, 'Multiple isolated worlds are not implemented');
-    return elementHandle;
-  }
-
   async waitForFrameNavigation(frame: frames.Frame, options: { timeout?: number; waitUntil?: string | Array<string>; } = {}) {
     const {
       timeout = this._timeoutSettings.navigationTimeout(),
diff --git a/src/firefox/JSHandle.ts b/src/firefox/JSHandle.ts
index c0abb32fd4..7fc9adc47f 100644
--- a/src/firefox/JSHandle.ts
+++ b/src/firefox/JSHandle.ts
@@ -16,24 +16,29 @@
  */
 
 import { assert, debugError } from '../helper';
-import * as js from '../javascript';
 import * as dom from '../dom';
 import * as input from '../input';
 import * as types from '../types';
 import * as frames from '../frames';
 import { JugglerSession } from './Connection';
 import { FrameManager } from './FrameManager';
-import { markJSHandle, ExecutionContextDelegate, toPayload } from './ExecutionContext';
+import { toPayload } from './ExecutionContext';
 
-class DOMWorldDelegate implements dom.DOMWorldDelegate {
+export class DOMWorldDelegate implements dom.DOMWorldDelegate {
+  readonly keyboard: input.Keyboard;
+  readonly mouse: input.Mouse;
+  readonly frame: frames.Frame;
   private _session: JugglerSession;
   private _frameManager: FrameManager;
   private _frameId: string;
 
-  constructor(session: JugglerSession, frameManager: FrameManager, frameId: string) {
-    this._session = session;
+  constructor(frameManager: FrameManager, frame: frames.Frame) {
+    this.keyboard = frameManager._page.keyboard;
+    this.mouse = frameManager._page.mouse;
+    this.frame = frame;
+    this._session = frameManager._session;
     this._frameManager = frameManager;
-    this._frameId = frameId;
+    this._frameId = frameManager._frameData(frame).frameId;
   }
 
   async contentFrame(handle: dom.ElementHandle): Promise<frames.Frame | null> {
@@ -129,26 +134,9 @@ class DOMWorldDelegate implements dom.DOMWorldDelegate {
   async setInputFiles(handle: dom.ElementHandle, files: input.FilePayload[]): Promise<void> {
     await handle.evaluate(input.setFileInputFunction, files);
   }
-}
 
-export function createHandle(context: js.ExecutionContext, result: any, exceptionDetails?: any) {
-  if (exceptionDetails) {
-    if (exceptionDetails.value)
-      throw new Error('Evaluation failed: ' + JSON.stringify(exceptionDetails.value));
-    else
-      throw new Error('Evaluation failed: ' + exceptionDetails.text + '\n' + exceptionDetails.stack);
-  }
-  if (result.subtype === 'node') {
-    const frame = context.frame();
-    const frameManager = frame._delegate as FrameManager;
-    const frameId = frameManager._frameData(frame).frameId;
-    const session = (context._delegate as ExecutionContextDelegate)._session;
-    const delegate = new DOMWorldDelegate(session, frameManager, frameId);
-    const handle = new dom.ElementHandle(context, frameManager._page.keyboard, frameManager._page.mouse, delegate);
-    markJSHandle(handle, result);
+  async adoptElementHandle(handle: dom.ElementHandle, to: dom.DOMWorld): Promise<dom.ElementHandle> {
+    assert(false, 'Multiple isolated worlds are not implemented');
     return handle;
   }
-  const handle = new js.JSHandle(context);
-  markJSHandle(handle, result);
-  return handle;
 }
diff --git a/src/firefox/Page.ts b/src/firefox/Page.ts
index 2aa3de2720..3a77f4555a 100644
--- a/src/firefox/Page.ts
+++ b/src/firefox/Page.ts
@@ -29,7 +29,6 @@ import { Accessibility } from './features/accessibility';
 import { Interception } from './features/interception';
 import { FrameManager, FrameManagerEvents, normalizeWaitUntil } from './FrameManager';
 import { RawMouseImpl, RawKeyboardImpl } from './Input';
-import { createHandle } from './JSHandle';
 import { NavigationWatchdog } from './NavigationWatchdog';
 import { NetworkManager, NetworkManagerEvents } from './NetworkManager';
 import * as input from '../input';
@@ -38,7 +37,7 @@ import * as dom from '../dom';
 import * as js from '../javascript';
 import * as network from '../network';
 import * as frames from '../frames';
-import { toPayload, deserializeValue } from './ExecutionContext';
+import { toHandle, toPayload, deserializeValue } from './ExecutionContext';
 
 const writeFileAsync = helper.promisify(fs.writeFile);
 
@@ -547,7 +546,7 @@ export class Page extends EventEmitter {
 
   _onConsole({type, args, executionContextId, location}) {
     const context = this._frameManager.executionContextById(executionContextId);
-    this.emit(Events.Page.Console, new ConsoleMessage(type, args.map(arg => createHandle(context, arg)), location));
+    this.emit(Events.Page.Console, new ConsoleMessage(type, args.map(arg => toHandle(context, arg)), location));
   }
 
   isClosed(): boolean {
@@ -571,7 +570,7 @@ export class Page extends EventEmitter {
     if (!this._fileChooserInterceptors.size)
       return;
     const context = this._frameManager.executionContextById(executionContextId);
-    const handle = createHandle(context, element) as dom.ElementHandle;
+    const handle = toHandle(context, element) as dom.ElementHandle;
     const interceptors = Array.from(this._fileChooserInterceptors);
     this._fileChooserInterceptors.clear();
     const multiple = await handle.evaluate((element: HTMLInputElement) => !!element.multiple);
diff --git a/src/frames.ts b/src/frames.ts
index fdeb4092fb..eff794c9db 100644
--- a/src/frames.ts
+++ b/src/frames.ts
@@ -48,7 +48,6 @@ export interface FrameDelegate {
   navigateFrame(frame: Frame, url: string, options?: GotoOptions): Promise<network.Response | null>;
   waitForFrameNavigation(frame: Frame, options?: NavigateOptions): Promise<network.Response | null>;
   setFrameContent(frame: Frame, html: string, options?: NavigateOptions): Promise<void>;
-  adoptElementHandle(elementHandle: dom.ElementHandle, context: js.ExecutionContext): Promise<dom.ElementHandle>;
 }
 
 export class Frame {
@@ -89,12 +88,26 @@ export class Frame {
     return this._worlds.get('main').contextPromise;
   }
 
+  async _mainDOMWorld(): Promise<dom.DOMWorld> {
+    const context = await this._mainContext();
+    if (!context._domWorld)
+      throw new Error(`Execution Context does not belong to frame`);
+    return context._domWorld;
+  }
+
   _utilityContext(): Promise<js.ExecutionContext> {
     if (this._detached)
       throw new Error(`Execution Context is not available in detached frame "${this.url()}" (are you trying to evaluate?)`);
     return this._worlds.get('utility').contextPromise;
   }
 
+  async _utilityDOMWorld(): Promise<dom.DOMWorld> {
+    const context = await this._utilityContext();
+    if (!context._domWorld)
+      throw new Error(`Execution Context does not belong to frame`);
+    return context._domWorld;
+  }
+
   executionContext(): Promise<js.ExecutionContext> {
     return this._mainContext();
   }
@@ -110,32 +123,32 @@ export class Frame {
   }
 
   async $(selector: string): Promise<dom.ElementHandle | null> {
-    const context = await this._mainContext();
-    const document = await context._document();
+    const domWorld = await this._mainDOMWorld();
+    const document = await domWorld._document();
     return document.$(selector);
   }
 
   async $x(expression: string): Promise<dom.ElementHandle[]> {
-    const context = await this._mainContext();
-    const document = await context._document();
+    const domWorld = await this._mainDOMWorld();
+    const document = await domWorld._document();
     return document.$x(expression);
   }
 
   $eval: types.$Eval = async (selector, pageFunction, ...args) => {
-    const context = await this._mainContext();
-    const document = await context._document();
+    const domWorld = await this._mainDOMWorld();
+    const document = await domWorld._document();
     return document.$eval(selector, pageFunction, ...args as any);
   }
 
   $$eval: types.$$Eval = async (selector, pageFunction, ...args) => {
-    const context = await this._mainContext();
-    const document = await context._document();
+    const domWorld = await this._mainDOMWorld();
+    const document = await domWorld._document();
     return document.$$eval(selector, pageFunction, ...args as any);
   }
 
   async $$(selector: string): Promise<dom.ElementHandle[]> {
-    const context = await this._mainContext();
-    const document = await context._document();
+    const domWorld = await this._mainDOMWorld();
+    const document = await domWorld._document();
     return document.$$(selector);
   }
 
@@ -293,8 +306,8 @@ export class Frame {
   }
 
   async click(selector: string, options?: ClickOptions) {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.click(options);
@@ -302,8 +315,8 @@ export class Frame {
   }
 
   async dblclick(selector: string, options?: MultiClickOptions) {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.dblclick(options);
@@ -311,8 +324,8 @@ export class Frame {
   }
 
   async tripleclick(selector: string, options?: MultiClickOptions) {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.tripleclick(options);
@@ -320,8 +333,8 @@ export class Frame {
   }
 
   async fill(selector: string, value: string) {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.fill(value);
@@ -329,8 +342,8 @@ export class Frame {
   }
 
   async focus(selector: string) {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.focus();
@@ -338,8 +351,8 @@ export class Frame {
   }
 
   async hover(selector: string, options?: PointerActionOptions) {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.hover(options);
@@ -347,14 +360,13 @@ export class Frame {
   }
 
   async select(selector: string, ...values: (string | dom.ElementHandle | SelectOption)[]): Promise<string[]> {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
-    const utilityContext = await this._utilityContext();
     const adoptedValues = await Promise.all(values.map(async value => {
       if (value instanceof dom.ElementHandle)
-        return this._adoptElementHandle(value, utilityContext, false /* dispose */);
+        return domWorld.adoptElementHandle(value, false /* dispose */);
       return value;
     }));
     const result = await handle.select(...adoptedValues);
@@ -363,8 +375,8 @@ export class Frame {
   }
 
   async type(selector: string, text: string, options: { delay: (number | undefined); } | undefined) {
-    const context = await this._utilityContext();
-    const document = await context._document();
+    const domWorld = await this._utilityDOMWorld();
+    const document = await domWorld._document();
     const handle = await document.$(selector);
     assert(handle, 'No node found for selector: ' + selector);
     await handle.type(text, options);
@@ -397,8 +409,8 @@ export class Frame {
       await handle.dispose();
       return null;
     }
-    const mainContext = await this._mainContext();
-    return this._adoptElementHandle(handle.asElement(), mainContext, true /* dispose */);
+    const mainDOMWorld = await this._mainDOMWorld();
+    return mainDOMWorld.adoptElementHandle(handle.asElement(), true /* dispose */);
   }
 
   async waitForXPath(xpath: string, options: {
@@ -411,8 +423,8 @@ export class Frame {
       await handle.dispose();
       return null;
     }
-    const mainContext = await this._mainContext();
-    return this._adoptElementHandle(handle.asElement(), mainContext, true /* dispose */);
+    const mainDOMWorld = await this._mainDOMWorld();
+    return mainDOMWorld.adoptElementHandle(handle.asElement(), true /* dispose */);
   }
 
   waitForFunction(
@@ -491,13 +503,4 @@ export class Frame {
         this._setContext(worldType, null);
     }
   }
-
-  private async _adoptElementHandle(elementHandle: dom.ElementHandle, context: js.ExecutionContext, dispose: boolean): Promise<dom.ElementHandle> {
-    if (elementHandle.executionContext() === context)
-      return elementHandle;
-    const handle = this._delegate.adoptElementHandle(elementHandle, context);
-    if (dispose)
-      await elementHandle.dispose();
-    return handle;
-  }
 }
diff --git a/src/javascript.ts b/src/javascript.ts
index 777040f1fa..edfe2ef493 100644
--- a/src/javascript.ts
+++ b/src/javascript.ts
@@ -4,9 +4,6 @@
 import * as frames from './frames';
 import * as types from './types';
 import * as dom from './dom';
-import * as injectedSource from './generated/injectedSource';
-import * as cssSelectorEngineSource from './generated/cssSelectorEngineSource';
-import * as xpathSelectorEngineSource from './generated/xpathSelectorEngineSource';
 
 export interface ExecutionContextDelegate {
   evaluate(context: ExecutionContext, returnByValue: boolean, pageFunction: string | Function, ...args: any[]): Promise<any>;
@@ -17,18 +14,15 @@ export interface ExecutionContextDelegate {
 }
 
 export class ExecutionContext {
-  _delegate: ExecutionContextDelegate;
-  private _frame: frames.Frame;
-  private _injectedPromise: Promise<JSHandle> | null = null;
-  private _documentPromise: Promise<dom.ElementHandle> | null = null;
+  readonly _delegate: ExecutionContextDelegate;
+  _domWorld?: dom.DOMWorld;
 
-  constructor(delegate: ExecutionContextDelegate, frame: frames.Frame | null) {
+  constructor(delegate: ExecutionContextDelegate) {
     this._delegate = delegate;
-    this._frame = frame;
   }
 
   frame(): frames.Frame | null {
-    return this._frame;
+    return this._domWorld ? this._domWorld.delegate.frame : null;
   }
 
   evaluate: types.Evaluate = (pageFunction, ...args) => {
@@ -38,29 +32,10 @@ export class ExecutionContext {
   evaluateHandle: types.EvaluateHandle = (pageFunction, ...args) => {
     return this._delegate.evaluate(this, false /* returnByValue */, pageFunction, ...args);
   }
-
-  _injected(): Promise<JSHandle> {
-    if (!this._injectedPromise) {
-      const engineSources = [cssSelectorEngineSource.source, xpathSelectorEngineSource.source];
-      const source = `
-        new (${injectedSource.source})([
-          ${engineSources.join(',\n')}
-        ])
-      `;
-      this._injectedPromise = this.evaluateHandle(source);
-    }
-    return this._injectedPromise;
-  }
-
-  _document(): Promise<dom.ElementHandle> {
-    if (!this._documentPromise)
-      this._documentPromise = this.evaluateHandle('document').then(handle => handle.asElement()!);
-    return this._documentPromise;
-  }
 }
 
 export class JSHandle {
-  _context: ExecutionContext;
+  readonly _context: ExecutionContext;
   _disposed = false;
 
   constructor(context: ExecutionContext) {
diff --git a/src/network.ts b/src/network.ts
index cb24994ecc..52ce335654 100644
--- a/src/network.ts
+++ b/src/network.ts
@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-import * as types from './types';
 import * as frames from './frames';
 
 export type NetworkCookie = {
diff --git a/src/webkit/ExecutionContext.ts b/src/webkit/ExecutionContext.ts
index 11ca2e0490..9ad3c53896 100644
--- a/src/webkit/ExecutionContext.ts
+++ b/src/webkit/ExecutionContext.ts
@@ -18,9 +18,9 @@
 import { TargetSession } from './Connection';
 import { helper } from '../helper';
 import { valueFromRemoteObject, releaseObject } from './protocolHelper';
-import { createJSHandle } from './JSHandle';
 import { Protocol } from './protocol';
 import * as js from '../javascript';
+import * as dom from '../dom';
 
 export const EVALUATION_SCRIPT_URL = '__playwright_evaluation_script__';
 const SOURCE_URL_REGEX = /^[\040\t]*\/\/[@#] sourceURL=\s*(\S*?)\s*$/m;
@@ -78,7 +78,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
         if (response.wasThrown)
           throw new Error('Evaluation failed: ' + response.result.description);
         if (!returnByValue)
-          return createJSHandle(context, response.result);
+          return toHandle(context, response.result);
         if (response.result.objectId) {
           const serializeFunction = function() {
             try {
@@ -184,7 +184,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
       if (response.wasThrown)
         throw new Error('Evaluation failed: ' + response.result.description);
       if (!returnByValue)
-        return createJSHandle(context, response.result);
+        return toHandle(context, response.result);
       if (response.result.objectId) {
         const serializeFunction = function() {
           try {
@@ -281,7 +281,7 @@ export class ExecutionContextDelegate implements js.ExecutionContextDelegate {
     for (const property of response.properties) {
       if (!property.enumerable)
         continue;
-      result.set(property.name, createJSHandle(handle.executionContext(), property.value));
+      result.set(property.name, toHandle(handle.executionContext(), property.value));
     }
     return result;
   }
@@ -338,6 +338,13 @@ export function toRemoteObject(handle: js.JSHandle): Protocol.Runtime.RemoteObje
   return (handle as any)[remoteObjectSymbol];
 }
 
-export function markJSHandle(handle: js.JSHandle, remoteObject: Protocol.Runtime.RemoteObject) {
+export function toHandle(context: js.ExecutionContext, remoteObject: Protocol.Runtime.RemoteObject) {
+  if (remoteObject.subtype === 'node' && context.frame()) {
+    const handle = new dom.ElementHandle(context);
+    (handle as any)[remoteObjectSymbol] = remoteObject;
+    return handle;
+  }
+  const handle = new js.JSHandle(context);
   (handle as any)[remoteObjectSymbol] = remoteObject;
+  return handle;
 }
diff --git a/src/webkit/FrameManager.ts b/src/webkit/FrameManager.ts
index 5e2f5aac2a..09425e5b1d 100644
--- a/src/webkit/FrameManager.ts
+++ b/src/webkit/FrameManager.ts
@@ -29,6 +29,7 @@ import { ExecutionContextDelegate } from './ExecutionContext';
 import { NetworkManager, NetworkManagerEvents } from './NetworkManager';
 import { Page } from './Page';
 import { Protocol } from './protocol';
+import { DOMWorldDelegate } from './JSHandle';
 
 export const FrameManagerEvents = {
   FrameNavigatedWithinDocument: Symbol('FrameNavigatedWithinDocument'),
@@ -235,8 +236,9 @@ export class FrameManager extends EventEmitter implements frames.FrameDelegate {
     const frame = this._frames.get(frameId) || null;
     if (!frame)
       return;
-    const context: js.ExecutionContext = new js.ExecutionContext(new ExecutionContextDelegate(this._session, contextPayload), frame);
+    const context = new js.ExecutionContext(new ExecutionContextDelegate(this._session, contextPayload));
     if (frame) {
+      context._domWorld = new dom.DOMWorld(context, new DOMWorldDelegate(this, frame));
       frame._contextCreated('main', context);
       frame._contextCreated('utility', context);
     }
@@ -272,11 +274,6 @@ export class FrameManager extends EventEmitter implements frames.FrameDelegate {
     return watchDog.waitForNavigation();
   }
 
-  async adoptElementHandle(elementHandle: dom.ElementHandle, context: js.ExecutionContext): Promise<dom.ElementHandle> {
-    assert(false, 'Multiple isolated worlds are not implemented');
-    return elementHandle;
-  }
-
   async setFrameContent(frame: frames.Frame, html: string, options: { timeout?: number; waitUntil?: string | Array<string>; } | undefined = {}) {
     // We rely upon the fact that document.open() will trigger Page.loadEventFired.
     const watchDog = new NextNavigationWatchdog(this, frame, 1000);
diff --git a/src/webkit/JSHandle.ts b/src/webkit/JSHandle.ts
index b25904dbc3..1b54585753 100644
--- a/src/webkit/JSHandle.ts
+++ b/src/webkit/JSHandle.ts
@@ -16,39 +16,29 @@
  */
 
 import * as fs from 'fs';
-import { debugError, helper } from '../helper';
+import { debugError, helper, assert } from '../helper';
 import * as input from '../input';
 import * as dom from '../dom';
 import * as frames from '../frames';
 import * as types from '../types';
 import { TargetSession } from './Connection';
-import { ExecutionContextDelegate, markJSHandle, toRemoteObject } from './ExecutionContext';
+import { toRemoteObject } from './ExecutionContext';
 import { FrameManager } from './FrameManager';
-import { Protocol } from './protocol';
-import * as js from '../javascript';
 
 const writeFileAsync = helper.promisify(fs.writeFile);
 
-export function createJSHandle(context: js.ExecutionContext, remoteObject: Protocol.Runtime.RemoteObject) {
-  const frame = context.frame();
-  if (remoteObject.subtype === 'node' && frame) {
-    const frameManager = frame._delegate as FrameManager;
-    const delegate = new DOMWorldDelegate((context._delegate as ExecutionContextDelegate)._session, frameManager);
-    const handle = new dom.ElementHandle(context, frameManager.page().keyboard, frameManager.page().mouse, delegate);
-    markJSHandle(handle, remoteObject);
-    return handle;
-  }
-  const handle = new js.JSHandle(context);
-  markJSHandle(handle, remoteObject);
-  return handle;
-}
-
-class DOMWorldDelegate implements dom.DOMWorldDelegate {
+export class DOMWorldDelegate implements dom.DOMWorldDelegate {
+  readonly keyboard: input.Keyboard;
+  readonly mouse: input.Mouse;
+  readonly frame: frames.Frame;
   private _client: TargetSession;
   private _frameManager: FrameManager;
 
-  constructor(client: TargetSession, frameManager: FrameManager) {
-    this._client = client;
+  constructor(frameManager: FrameManager, frame: frames.Frame) {
+    this.keyboard = frameManager.page().keyboard;
+    this.mouse = frameManager.page().mouse;
+    this.frame = frame;
+    this._client = frameManager._session;
     this._frameManager = frameManager;
   }
 
@@ -124,8 +114,8 @@ class DOMWorldDelegate implements dom.DOMWorldDelegate {
     // Filter out quads that have too small area to click into.
     const {clientWidth, clientHeight} = viewport;
     const quads = result.quads.map(fromProtocolQuad)
-      .map(quad => intersectQuadWithViewport(quad, clientWidth, clientHeight))
-      .filter(quad => computeQuadArea(quad) > 1);
+        .map(quad => intersectQuadWithViewport(quad, clientWidth, clientHeight))
+        .filter(quad => computeQuadArea(quad) > 1);
     if (!quads.length)
       throw new Error('Node is either not visible or not an HTMLElement');
     // Return the middle point of the first quad.
@@ -146,4 +136,9 @@ class DOMWorldDelegate implements dom.DOMWorldDelegate {
     const objectId = toRemoteObject(handle).objectId;
     await this._client.send('DOM.setInputFiles', { objectId, files });
   }
+
+  async adoptElementHandle(handle: dom.ElementHandle, to: dom.DOMWorld): Promise<dom.ElementHandle> {
+    assert(false, 'Multiple isolated worlds are not implemented');
+    return handle;
+  }
 }
diff --git a/src/webkit/Page.ts b/src/webkit/Page.ts
index 407e3b3406..ffe9c2ff90 100644
--- a/src/webkit/Page.ts
+++ b/src/webkit/Page.ts
@@ -26,8 +26,7 @@ import { TargetSession, TargetSessionEvents } from './Connection';
 import { Events } from './events';
 import { FrameManager, FrameManagerEvents } from './FrameManager';
 import { RawKeyboardImpl, RawMouseImpl } from './Input';
-import { createJSHandle } from './JSHandle';
-import { toRemoteObject } from './ExecutionContext';
+import { toHandle, toRemoteObject } from './ExecutionContext';
 import { NetworkManagerEvents } from './NetworkManager';
 import { Protocol } from './protocol';
 import { valueFromRemoteObject } from './protocolHelper';
@@ -183,7 +182,7 @@ export class Page extends EventEmitter {
       } else {
         context = mainFrameContext;
       }
-      return createJSHandle(context, p);
+      return toHandle(context, p);
     });
     const textTokens = [];
     for (const handle of handles) {
@@ -462,7 +461,7 @@ export class Page extends EventEmitter {
     if (!this._fileChooserInterceptors.size)
       return;
     const context = await this._frameManager.frame(event.frameId)._utilityContext();
-    const handle = createJSHandle(context, event.element) as dom.ElementHandle;
+    const handle = toHandle(context, event.element) as dom.ElementHandle;
     const interceptors = Array.from(this._fileChooserInterceptors);
     this._fileChooserInterceptors.clear();
     const multiple = await handle.evaluate((element: HTMLInputElement) => !!element.multiple);
diff --git a/utils/doclint/check_public_api/JSBuilder.js b/utils/doclint/check_public_api/JSBuilder.js
index 5f812e6db0..860c77d30f 100644
--- a/utils/doclint/check_public_api/JSBuilder.js
+++ b/utils/doclint/check_public_api/JSBuilder.js
@@ -104,12 +104,14 @@ function checkSources(sources) {
   function parentClass(classNode) {
     for (const herigateClause of classNode.heritageClauses || []) {
       for (const heritageType of herigateClause.types) {
-        const parentClassName = heritageType.expression.escapedText;
-        return parentClassName;
+        let expression = heritageType.expression;
+        if (expression.kind === ts.SyntaxKind.PropertyAccessExpression)
+          expression = expression.name;
+        if (classNode.name.escapedText !== expression.escapedText)
+          return expression.escapedText;
       }
     }
     return null;
-
   }
 
   function serializeSymbol(symbol, circular = []) {