Suppress timeouts on Windows browser bots when dart2js hangs.
Suppress timeouts on Windows browser bots when dart2js hangs.

Also run dartfmt on test_runner.dart file.

BUG=https://github.com/dart-lang/sdk/issues/26060
R=sgjesse@google.com

Review URL: https://codereview.chromium.org/2105783002 .

dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk