Implement Symbol correctly in dart2js.

dart/pkg/pkg.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.
 
 serialization/test/*: Skip # http://dartbug.com/9894
 
 
 # Run this test manually to verify that the fixnum library produces
 # the same results as native ints on a set of directed and random inputs.
 # Skip it when running automated tests because it times out.  This
@@ skipping 99 matching lines @@
 analyzer_experimental/test/generated/resolver_test: Skip
 analyzer_experimental/test/generated/scanner_test: Skip
 
 [ $compiler == dartc ]
 unittest/test/mock_regexp_negative_test: Fail
 unittest/test/mock_stepwise_negative_test: Fail
 
 
 [ $compiler == dart2js ]
 unittest/test/instance_test: Skip
-unittest/test/mock_test: Fail # MirrorSystem.getName not yet implemented in dart2js.
+
 
 [ $compiler == dart2js && $runtime == drt ]
 intl/test/date_time_format_uninitialized_test: Pass, Fail # http://dartbug.com/9000
 
 [ $compiler == dart2js && $minified ]
 # The unittest package relies on getting the original (non-minified) method
 # names in Invocation.  You can't get that when minifying.
 # TODO(ahe/erikcorry): But soon you can, now that we use Symbol.
 unittest/test/mock_test: Fail
 
@@ skipping 12 matching lines @@
 [ $arch == mips ]
 *: Skip
 
 [ $arch == simmips ]
 *: Skip
 
 # Skip serialization test that explicitly has no library declaration in the
 # test on Dartium, which requires all tests to have a library.
 [ $runtime == dartium || $runtime == drt ]
 serialization/test/no_library_test: Skip # Expected Failure