Since Dart `void` can actually carry values, functions with `void`
return type are translated into Wasm functions returning the Dart
object top type instead of an empty output type list.
Only constructors, setters and imports/exports with void return type
are now given empty output type lists in their Wasm signatures. A new
low-level `WasmVoid` type is added to the internal Wasm types for
specifying explicitly that a Wasm function should have an empty list
of outputs.
Fixes https://github.com/dart-lang/sdk/issues/50458
CoreLibraryReviewExempt: Only changes Wasm-specific libraries.
Change-Id: I9562248f94e75a60142fd1af0136183aa288b98b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/279971
Reviewed-by: Ömer Ağacan <omersa@google.com>
Commit-Queue: Aske Simon Christensen <askesc@google.com>
Aske Simon Christensen
bc31fe4903