Implement math.gcd in 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.
 
 # Don't run any test-like files that show up in packages directories. It
 # shouldn't be necessary to run "pub install" in these packages, but if you do
 # it shouldn't break the tests.
 */packages/*/*: Skip
 */*/packages/*/*: Skip
 */*/*/packages/*/*: Skip
@@ skipping 81 matching lines @@
 [ $compiler == dart2js ]
 collection/test/equality_test/01: Fail # Issue 1533
 collection/test/equality_test/02: Fail # Issue 1533
 collection/test/equality_test/03: Fail # Issue 1533
 collection/test/equality_test/04: Fail # Issue 1533
 collection/test/equality_test/05: Fail # Issue 1533
 collection/test/equality_test/none: Pass, Fail # Issue 14348
 docgen/test/*: Skip # Far too slow
 third_party/angular_tests/browser_test: Pass, Slow # Large dart2js compile time
 typed_data/test/typed_buffers_test/01: Fail # Not supporting Int64List, Uint64List.
+math/test/bigint_test: RuntimeError # Requires bigint support.
 
 analysis_server/test/search/element_references_test: Pass, Slow
 analysis_server/test/services/index/store/codec_test: Pass, Slow
 
 # Analysis server integration tests don't make sense to run under
 # dart2js, since the code under test always runs in the Dart vm as a
 # subprocess.
 analysis_server/test/integration: Skip
 
 [ $compiler == dart2js && $runtime == ff && $system == windows ]
@@ skipping 359 matching lines @@
 oauth2/test/authorization_code_grant_test: Fail
 oauth2/test/client_test: Fail
 oauth2/test/credentials_test: Fail
 oauth2/test/handle_access_token_response_test: Fail
 
 [ $runtime == drt ]
 http/test/html/client_test: Skip # Issue 18566
 
 [ $system == windows ]
 analysis_server/test/integration/search/get_type_hierarchy_test: Pass, Fail # Issue 20436