Make 'class' and 'extends' into real keywords, per language spec 0.06 .

tests/language/language.status

 # Copyright (c) 2011, 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.
 
 # In order to maintain maximum test coverage for all builds,
 # please use the following procedure to mark a test
 # failed on architectures other than the one you are working on.
@@ skipping 174 matching lines @@
 [ $component == frogsh ||  $component == frog || $component == webdriver || $component == frogium ]
 # TODO(efortuna): Distinguish between specific browser being run for webdriver
 # (by flag option) to specify which tests pass.
 FactoryNegativeTest: Fail # Issue 417
 Factory3Test: Fail # Issue 417
 CallThroughNullGetterTest: Fail # Throw ObjectNotClosure instead of NullPointerException.
 OptimizedSetterTest: Fail # Issue 863
 
 FactoryImplementationTest: Fail # Issue 523
 
-ClassKeywordTest/01: Fail # Issue 874
-
 # VM or DartC specific tests not to be run by Frog. See language.status
 *VMTest: Skip
 *VMNegativeTest: Skip
 *DartcTest: Skip
 *DartcNegativeTest: Skip
 # Currently, these patterns skip three tests:
 # MathVMTest - correctly skipped as this relies on VM guarantees
 #    - should add a version of this with the --enable_type_checks flag
 # TypeVMTest - correctly skipped as this relies on detailed of TypeError
 # TypeDartcTest - should pass, need refactoring to get frog safe version
@@ skipping 129 matching lines @@
 NumberSyntaxTest: Timeout
 
 [ $arch == x64 ]
 *: Skip
 
 [ $arch == simarm ]
 *: Skip
 
 [ $arch == arm ]
 *: Skip