[CP] [dart2wasm] Make `dart compile wasm` compiled apps disable `dart.library.ffi`

[mkustermann]

Commit(s) to merge

847c356

Target

stable

Prepared changelist for beta/stable

https://dart-review.googlesource.com/c/sdk/+/370880

Issue Description

Packages on pub use conditional imports that branch on dart.library.ffi. The ffi-specific code is meant to be run on the VM. Unfortunately currently this also evaluates to true in dart2wasm, which makes apps that work with dart2js not work with dart2wasm due to different evaluation of the conditional import.

What is the fix

Change dart2wasm to make this conditional import evaluate to false.

Why cherry-pick

Users are hitting this when using package:flutter_svg which uses package:vector_graphics_compiler which uses `dart:ffi.

Risk

As always: If CI passes the risk is low.

Issue link(s)

#55948

Extra Info

No response

[mkustermann]

/cc @athomas for awareness

If flutter also releases a new stable with this CP in, it may need to cherry-pick:

• in engine flutter/engine@1f3938d & flutter/engine@ae9e092 (get rid of dart.library.ffi conditional imports usage in engine)
• in framework flutter/flutter@c0b2645 (gets rid of const bool.fromEnvironment('dart.library.ffi') usage in framework)

[mit-mit]

sgtm

[athomas]

LGTM

[mkustermann]

The CL landed.

[mkustermann]

I believe this was released yesterday with Dart SDK 3.4.4 . So we can close this.