- Do not resolve raw headers upon `loadingFinished`, since they may still come later in
`responseReceivedExtraInfo`.
- Introduce separate promises for `encodedBodySize`, `transferSize` and `responseHeadersSize`.
- Make sure we resolve each of them either with data available
from the browser, or a fallback calculation.
- Set raw response headers for redirects on WebKit.
- Do not stall on cached responses in Chromium, they have erroneously set `hasExtraInfo` flag.
- Use `transferSize` that is available in Firefox protocol.
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