Yury Semikhatsky 6c3142959d
fix(blob): store startTime as a number (#24620)
Turns out the Date objects have noticeable footprint on large suites and
storing them as umber is much cheaper, e.g.:


![image](https://github.com/microsoft/playwright/assets/9798949/539028d0-3ef8-46f7-be2b-752f24604d18)
2023-08-04 16:06:23 -07:00
..
2023-08-04 14:59:48 -07:00
2023-08-04 14:59:48 -07:00
2023-07-31 11:24:04 -07:00