Linux Web Framework tests flaky due to timeout interactions with loading the tests #126178
Description
We are seeing these kinds of failures a lot lately and it looks like the issue is that the Dart mechanism used to load all of the tests has a 12m timeout to load all of the tests that it was given, but we are blocking each test loaded by running the tests in it which means we reach the 12m timeout for loading before the test is done and well before the test has a CI timeout.
12:00 +133 ~2 -1: compiling /b/s/w/ir/x/w/flutter/packages/flutter/test/widgets/slivers_appbar_stretch_test.dart [E]
TimeoutException after 0:12:00.000000: Test timed out after 12 minutes.
package:test_api/src/backend/invoker.dart 338:28 Invoker._handleError.<fn>
dart:async/zone.dart 1391:47 _rootRun
dart:async/zone.dart 1301:19 _CustomZone.run
package:test_api/src/backend/invoker.dart 336:10 Invoker._handleError
package:test_api/src/backend/invoker.dart 291:9 Invoker.heartbeat.<fn>.<fn>
dart:async/zone.dart 1399:13 _rootRun
dart:async/zone.dart 1301:19 _CustomZone.run
package:test_api/src/backend/invoker.dart 290:38 Invoker.heartbeat.<fn>
dart:async-patch/timer_patch.dart 18:15 Timer._createTimer.<fn>
dart:isolate-patch/timer_impl.dart 398:19 _Timer._runTimers
dart:isolate-patch/isolate_patch.dart 189:12 _RawReceivePort._handleMessage
To run this test again: /b/s/w/ir/x/w/flutter/bin/cache/dart-sdk/bin/dart test /b/s/w/ir/x/w/flutter/packages/flutter/test/widgets/slivers_appbar_stretch_test.dart -p chrome --plain-name 'compiling /b/s/w/ir/x/w/flutter/packages/flutter/test/widgets/slivers_appbar_stretch_test.dart'
[ Same failure message repeated for a dozen or more tests following this one ]
See Linux Web Framework tests log output: https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8781923893844814817/+/u/run_test.dart_for_web_tests_shard_and_subshard_4/test_stdout