[CP] dart2wasm async and sync* fixes to stable

[osa1]

Commit(s) to merge

6de879e, 7e237a1, eabb2b3, e44bc22, 350954a, 8ccb412, e7dde83, 3863e78, 829261e, fab56db

Target

stable

Prepared changelist for beta/stable

https://dart-review.googlesource.com/c/sdk/+/368300

Issue Description

Users are currently missing a lot of async and sync* bug fixes, and unable to use exception handling (try/catch) or switch statements (when the statement has a yield in the body).

What is the fix

Cherry pick the fixes and implementations.

Why cherry-pick

Users are missing bug fixes and some of the sync* features are simply unimplemented in the latest release.

Risk

Medium. While these changes include a lot of refactoring, no new features were added and a lot of bugs were fixed.

Issue link(s)

#55347, #55457, #51343, #51342 and probably more. (some of the fix commits didn't link to issues)

Extra Info

No response

[mkustermann]

LGTM

Since CI is green on this CP, I have no worries about it being risky. It CL looks big but

• it's mostly moving code from one place to another (i.e. includes a refactoring)
• fixes a number of issues (i.e. makes our stable branch more stable - which is it's purpose)
• it makes the code on stable branch closer to main, so any future CPs, will get easier to merge if need be (**)

(**) The alternative is to hand-craft a fix for stable channel, which could make the CL a bit smaller, but will cause diverging of the main & stable branches.

[osa1]

Cherry-pick merged as fbbb836.

[mkustermann]

I think the issue stays open until it was released on stable (see https://github.com/dart-lang/sdk/blob/main/docs/Cherry-picks-to-a-release-channel.md#submitting-the-cherry-pick)