[dart2wasm] Mark timing out test as SkipSlow on all browsers, not just Chrome

The root cause is that an `asyncEnd()` doesn't get executed which
will make the test not print `unittest-suite-success` which will
make the test controller keep waiting indefinitly until the test
times out.
=> This is true on all browsers, not just Chrome

Though commandline JS engines don't have this problem as they will
simply exit once there's no longer work and event loop is empty.

=> Here the test runner will recognize the missing
   `unittest-suite-success` and report the tests as failing.

Issue #55182

Change-Id: Id217e9bd715d99f9927e7e18b03385aa2880b27f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/404107
Reviewed-by: Ömer Ağacan <[email protected]>
Commit-Queue: Martin Kustermann <[email protected]>

Author: mkustermann

tests/co19/co19-dart2wasm.status

@@ -15,5 +15,5 @@ LibTest/io/*: SkipByDesign # dart:io is not supported.
 LibTest/isolate/*: SkipByDesign # dart:isolate is not supported.
 LibTest/mirrors/*: SkipByDesign # dart:mirrors is not supported.
 
-[ $compiler == dart2wasm && $runtime == chrome ]
-Language/Expressions/Function_Invocation/async_generator_invokation_t10: SkipSlow # Issue(http://dartbug.com/55025)
+[ $compiler == dart2wasm && $browser ]
+Language/Expressions/Function_Invocation/async_generator_invokation_t10: SkipSlow # Issue(http://dartbug.com/55182): Will timeout on browsers (due to no asyncEnd() firing) but eagerly fail on commandline JS engines.