dart2js: Bugfix for when 'await' occurs in an initializer list.

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.
 
 [ $unchecked ]
 mirrors/redirecting_factory_different_type_test: SkipByDesign # Tests type checks.
 
 [ $compiler == dart2js ]
 async/schedule_microtask6_test: RuntimeError # global error handling is not supported. Issue 5958
 
@@ skipping 320 matching lines @@
 
 [ $mode == debug && $arch != ia32 && $arch != x64 && $arch != simarm && $arch != simarmv5te ]
 convert/streamed_conversion_json_utf8_decode_test: Skip  # Verification not yet implemented.
 
 [ $runtime == vm && $mode == debug && $builder_tag == asan ]
 mirrors/immutable_collections_test: SkipSlow  # Timeout.
 convert/streamed_conversion_json_utf8_decode_test: Skip  # Timeout.
 
 [ $compiler == dart2js && $cps_ir ]
 async/async_await_zones_test: Crash # (await for(var x in bar().take(100)){sum+= x;}): await for
-async/stream_empty_test: RuntimeError # $async$temp1.runTest_unreachable is not a function
 async/stream_iterator_test: Crash # (Stream createCancel...  cannot handle sync*/async* functions
 convert/json_pretty_test: RuntimeError # Please triage this failure.
 convert/line_splitter_test: RuntimeError # Please triage this failure.
 mirrors/deferred_mirrors_metadata_test: RuntimeError # U.loadLibrary is not a function
 mirrors/deferred_mirrors_metatarget_test: RuntimeError # X.loadLibrary is not a function
 mirrors/deferred_mirrors_update_test: RuntimeError # U.loadLibrary is not a function
 mirrors/delegate_call_through_getter_test: RuntimeError # Please triage this failure.
 mirrors/delegate_test: RuntimeError # Please triage this failure.
 mirrors/library_enumeration_deferred_loading_test: RuntimeError # L.loadLibrary is not a function
 mirrors/symbol_validation_test/none: RuntimeError # Please triage this failure.
 mirrors/typedef_deferred_library_test: RuntimeError # G.loadLibrary is not a function
 
 [ $compiler == dart2js && $cps_ir && $host_checked ]
 mirrors/circular_factory_redirection_test/02: Crash # Assertion failure: Constant constructor already computed for generative_constructor(A#circular2)
 mirrors/mirrors_used_typedef_declaration_test/01: Crash # Assertion failure: typedef(Foo) has not been checked for cycles.
 mirrors/mirrors_used_typedef_declaration_test/none: Crash # Assertion failure: typedef(Foo) has not been checked for cycles.
 mirrors/typedef_library_test: Crash # Assertion failure: typedef(G) has not been checked for cycles.
 
 [ $noopt ]
 mirrors/*: SkipByDesign
 convert/chunked_conversion_utf88_test: Pass, Timeout
 convert/utf85_test: Pass, Timeout