[CP] Check dart:ffi imports and wasm:import/export pragmas in user code #55890
Description
Commit(s) to merge
Target
stable
Prepared changelist for beta/stable
https://dart-review.googlesource.com/c/sdk/+/369040
Issue Description
dart2wasm currently allows importing dart:ffi (to use @Native) and using wasm:import and wasm:export pragmas.
However none of these were designed for end users. We have no documentation on how to properly use them, and they can cause compile time or runtime crashes.
What is the fix
Disallow importing dart:ffi and using wasm:import and wasm:export pragmas.
Why cherry-pick
These features were never intended for users. They will cause confusion.
Risk
None, however we should make sure the checks allow uses of these features in Flutter.
Issue link(s)
Extra Info
No response