Fix timer tests: timer tests were not using expectAsync to wait for

tests/isolate/isolate.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.
 
 [ $runtime == vm ]
 isolate2_negative_test: Skip  # Need to resolve correct behaviour.
 serialization_test: Skip  # tests dart2js-specific serialization code
 spawn_uri_test: Fail, OK # test uses a ".js" suffix that is bogus on vm.
 compute_this_script_browser_test: Skip # browser specific test
 timer_not_available_test: Fail, OK # only meant to test when there is no way to
@@ skipping 19 matching lines @@
 
 [ $compiler == dart2js ]
 serialization_test: Fail # Tries to access class TestingOnly declared in isolate_patch.dart
 
 [ $runtime == safari ]
 cross_isolate_message_test: Skip      # Depends on 32/64 bit Safari. See Issue 1120
 mixed_test: Pass,Fail               # Depends on 32/64 bit Safari. See Issue 1120
 mixed2_test: Pass,Fail              # Depends on 32/64 bit Safari. See Issue 1120
 message_test: Skip
 
+[ $runtime == ff ]
+# FF setTimeout can fire early: https://bugzilla.mozilla.org/show_bug.cgi?id=291386
+timer_test: Pass, Fail
+multiple_timer_test: Pass, Fail
+
 # TODO(ager): Update these.
 [ $runtime == ie && $system == windows ]
 v2*: Skip
 
 [ $runtime == safari && $system == macos ]
 v2*: Skip
 
 [ $runtime == ie && ($system == linux || $system == macos) ]
 *: Skip
 
@@ skipping 29 matching lines @@
 multiple_timer_test: Fail,OK # Needs Timer to run.
 timer_test: Fail,OK # Needs Timer to run.
 timer_repeat_test: Fail,OK # Needs Timer to run.
 
 [ $compiler == dart2js && $runtime == none ]
 *: Fail, Pass # TODO(ahe): Triage these tests.
 
 [ $compiler == dart2dart ]
 # Skip until we stabilize language tests.
 *: Skip