Fully reland https://github.com/flutter/engine/pull/45300

[dkwingsmt]

I'm working on fully relanding flutter/engine#45300, which was reverted in flutter/engine#46919 due to performance regression.

Due to how little and trivial production code the original PR touches, I really couldn't figure out the exact line that caused it except through experimentation: I'll reland the changes bit by bit, and perform performance test after each land, since the performance test requires changes to be officially landed on the main branch.

[flutter-triage-bot]

This issue is marked P1 but has had no recent status updates.

The P1 label indicates high-priority issues that are at the top of the work list. This is the highest priority level a bug can have if it isn't affecting a top-tier customer or breaking the build. Bugs marked P1 are generally actively being worked on unless the assignee is dealing with a P0 bug (or another P1 bug). Issues at this level should be resolved in a matter of months and should have monthly updates on GitHub.

Please consider where this bug really falls in our current priorities, and label it or assign it accordingly. This allows people to have a clearer picture of what work is actually planned. Thanks!

[dkwingsmt]

This issue is obsolete since we're no longer seeking to reland the said PR.