- Keep main frames in a separate bucket, so that page methods that
redirect to the main frame continue to work.
- Increase default dispatchers limit to `10_000`.
- Increase dispatchers limit for `JSHandle`/`ElementHandle` to
`100_000`.
Fixes#28320, #28503.
Partial fix for https://github.com/microsoft/playwright/issues/6319
After this fix, the following scenario won't leak and the context state
(cookies, storage, etc) can be reused by the new page sessions:
```js
for (let i = 0; i < 1000; ++i) {
const page = await context.newPage();
await page.goto('...');
await page.close('...');
}
```
