Skip double reporting tests on dart2js configurations.

tests/co19/co19-dart2js.status

Index: tests/co19/co19-dart2js.status
diff --git a/tests/co19/co19-dart2js.status b/tests/co19/co19-dart2js.status
index 4ab8af86cb7130b9038c44cbbcce805b48ae26ae..8b3c2359764183d0b48c87b867a66832db04b955 100644
--- a/tests/co19/co19-dart2js.status
+++ b/tests/co19/co19-dart2js.status
@@ -3,6 +3,12 @@
 # BSD-style license that can be found in the LICENSE file.
 
 [ $compiler == dart2js ]
+Language/Expressions/Function_Invocation/async_cleanup_t03: Skip # https://github.com/dart-lang/sdk/issues/28873
+Language/Expressions/Function_Invocation/async_cleanup_t06: Skip # https://github.com/dart-lang/sdk/issues/28873
+LayoutTests/fast/dom/HTMLLinkElement/link-onload-stylesheet-with-import_t01: Skip # https://github.com/dart-lang/sdk/issues/28873
+LayoutTests/fast/table/hittest-tablecell-with-borders-right-edge_t01: Skip # https://github.com/dart-lang/sdk/issues/28873
+LayoutTests/fast/text/zero-width-characters-complex-script_t01.dart: Skip # https://github.com/dart-lang/sdk/issues/28873
+LibTest/html/Window/postMessage_A01_t01: Skip # https://github.com/dart-lang/sdk/issues/28873
 
 Language/Classes/Constructors/Generative_Constructors/execution_of_a_superinitializer_t01: RuntimeError # compiler cancelled: cannot resolve type T
 Language/Classes/Constructors/Generative_Constructors/execution_of_a_superinitializer_t01: RuntimeError, OK # co19 issue 258