core(total-byte-weight): count partially finished requests

[patrickhulce]

Summary
Removes the total byte weight policy that ignored partially downloaded resources (like videos). IMO, this dramatically understates the weight of a page in some cases (see #12664).

The check was added way back in 2017 by me as part of adding visibility into inflight records 🤯 . This was also before we used our own network request class that initializes transferSize that prevents the undefined concern that prompted the original.

Nonetheless, I added a test to ensure spirit of the condition is still handled.

Related Issues/PRs
closes #12664

[connorjclark]

I didn't understand the note about undefined. Why does this need to change?

Don't need to do typeof here, just networkRecord.transferSize === undefined works. Or if the data type is somehow uncertain, flip the logic to typeof networkRecord.transferSize === 'number' ? networkRecord.transferSize : 0.

[patrickhulce]

Don't need to do typeof here

ah yes, old habits :)

Or if the data type is somehow uncertain, flip the logic to

The spirit of the original I assumed was ?? 0, i.e. use 0 as a default if some value is not explicitly set. That seems better than ignoring all values that aren't numbers.

I didn't understand the note about undefined. Why does this need to change?

If we are ever to test unexpected values coming from the protocol, we need a mechanism to mock those values in the devtools log. The affected code was attempting to handle such unexpected values.