Restore firefox browser to pkg/third_party/angular_tests suppression.

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 325 matching lines @@
 
 [ $compiler == dartanalyzer || $compiler == dart2analyzer ]
 matcher/test/matchers_test: StaticWarning, OK # testing error creating abstract class
 
 [ $runtime == vm && ($system == windows || $system == macos) ]
 watcher/test/*/linux_test: Skip
 
 [ $runtime == vm && ($system == windows || $system == linux) ]
 watcher/test/*/mac_os_test: Skip
 
-[ $runtime == safari || $runtime == chrome || $ie ]
+[ $runtime == safari || $runtime == chrome || $runtime == ff || $ie ]
 # Various issues due to limited browser testing in Angular.
 third_party/angular_tests/*: Skip
 
 [ $unchecked ]
 third_party/angular_tests/browser_test/angular: Skip # Requires checked mode.
 third_party/angular_tests/browser_test/core/scope: Skip # Requires checked mode.
 third_party/angular_tests/browser_test/core/zone: Skip # Requires checked mode.
 third_party/angular_tests/browser_test/directive/ng_repeat: Skip # Issue 17152
 third_party/angular_tests/browser_test/change_detection/dirty_checking_change_detector: Skip # Issue 17152
 
@@ skipping 19 matching lines @@
 collection/test/priority_queue_test: PubGetError
 collection/test/unmodifiable_collection_test: PubGetError
 collection/test/wrapper_test: PubGetError
 stack_trace/test/chain_test: PubGetError
 stack_trace/test/frame_test: PubGetError
 stack_trace/test/trace_test: PubGetError
 stack_trace/test/vm_test: PubGetError
 
 [ $runtime == ie9 ]
 polymer: Pass, Fail, Timeout # Issue 16717