dart2js: allow trailing commas in parameter and argument lists

tests/language/language.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.
 
 # This directory contains tests that are intended to show the
 # current state of the language.
 
 # Trailing commas are so far supported by:
 # - The VM (vm, dartium, drt, precompiler+dart_precompiled)
+# - dart2js
 # Remaining targets still fail on arg_param_trailing_comma_test/none.
-[($compiler != none && $compiler != precompiler) || ($runtime != vm && $runtime != dartium && $runtime != drt && $runtime != dart_precompiled)]
+[ $compiler == dart2analyzer ]
 arg_param_trailing_comma_test/none: Fail # Issue 26644
 
 [ ($compiler == none || $compiler == precompiler || $compiler == dart2app || $compiler == dart2appjit) ]
 tearoff_constructor_basic_test: Skip # Crashes in checked mode -- hausner investigating
 
 # These tests are skipped in the VM because it has "--supermixin"
 # functionality enabled unconditionally.  The tests should be removed
 # once the same is true for analyzer (#24478) and dart2js (#23773)
 mixin_illegal_super_use_test: Skip # Issues 24478 and 23773
 mixin_illegal_superclass_test: Skip # Issues 24478 and 23773
@@ skipping 226 matching lines @@
 large_class_declaration_test: Skip
 
 [ $compiler == precompiler && $runtime == dart_precompiled && $system == android ]
 vm/optimized_guarded_field_isolates_test: Skip # Issue #26373
 issue23244_test: Skip # Issue #26373
 
 [ $hot_reload ]
 deferred_load_inval_code_test: RuntimeError
 regress_26453_test: Pass, Fail, Crash
 vm/regress_16873_test: Pass, Crash