dart2js: jsshell is not yet implementing scheduleMicrotask correctly.

tests/lib/lib.status

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 [ $checked && $compiler != dartanalyzer && $compiler != dart2analyzer && $runtime != dartium ]
 mirrors/regress_16321_test/01: CompileTimeError # Issue 16351
 
 [ $checked && $compiler == none && ($runtime == dartium || $runtime == drt) ]
 mirrors/regress_16321_test/01: RunTimeError # Issue 16351
 
@@ skipping 273 matching lines @@
 mirrors/mirrors_reader_test: Skip # Times out. Issue 20806.
 
 [ $compiler == dart2dart ]
 # Deferred loading is not supported by dart2dart.
 async/deferred/deferred_in_isolate_test: Skip # Issue 17523
 
 [ $compiler == none && ($runtime == drt || $runtime == dartium || $runtime == ContentShellOnAndroid) ]
 # Dart vm does not support spawn from a dom-enabled isolate.
 async/deferred/deferred_in_isolate_test: RuntimeError # Issue 16209
 
+[ $compiler == dart2js && $runtime == jsshell ]
+async/schedule_microtask_test: Fail  # Preamble file does not correctly implement scheduleImmediate.
+
 [ $compiler == dartanalyzer || $compiler == dart2analyzer ]
 mirrors/generic_f_bounded_mixin_application_test: StaticWarning # Test Issue
 
 mirrors/redirecting_factory_test/01: StaticWarning # test issue X, The return type 'Class<T2, T1>' of the redirected constructor is not assignable to 'Class<T1, T2>'
 mirrors/redirecting_factory_test/none: StaticWarning # test issue X, The return type 'Class<T2, T1>' of the redirected constructor is not assignable to 'Class<T1, T2>
 
 mirrors/immutable_collections_test: StaticWarning, OK # Expect failure for any type of Iterable.
 mirrors/inference_and_no_such_method_test: StaticWarning, OK # Expect to trigger noSuchMethod.
 mirrors/mirrors_nsm_test: StaticWarning, OK # Expect to trigger noSuchMethod.
 
@@ skipping 18 matching lines @@
 
 [ $arch == simarm ]
 convert/chunked_conversion_utf88_test: Skip  # Pass, Slow Issue 12644.
 convert/utf85_test: Skip  # Pass, Slow Issue 12644.
 
 [ $compiler == dart2js ]
 profiler/metrics_num_test: Skip # Because of a int / double type test.
 
 [ $arch == simarm64 ]
 convert/utf85_test: Skip # Pass, Slow Issue 20111.