[CP] [dart2wasm] Fix bug in setter type checker argument checking implementation #56374
Description
Commit(s) to merge
Target
stable
Prepared changelist for beta/stable
Issue Description
Flutter code that uses dynamic calls where the dynamic call targets a setter with a generic argument will (in -O3 / -O4 mode - the ladder which is flutter builds default) sets null instead of the actual value.
What is the fix
Make compiler in -O3 / -O4 mode correctly set the field value in the implicit setter.
Why cherry-pick
Flutter users have hit this.
Risk
If tests pass: low
Issue link(s)
Extra Info
No response