Add Zone support for Timers.

sdk/lib/_internal/compiler/implementation/lib/async_patch.dart

Index: sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart b/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
index 9d8b237ef4bea4a38cab51ecaf3c21e29984d3ed..22872b97e60c810865afbb5fffb0464730ba20d2 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/async_patch.dart
@@ -7,18 +7,17 @@
 import 'dart:_isolate_helper' show IsolateNatives, TimerImpl;
 import 'dart:_foreign_helper' show JS, DART_CLOSURE_TO_JS;
 
-patch class Timer {
-  patch factory Timer(Duration duration, void callback()) {
-    int milliseconds = duration.inMilliseconds;
-    if (milliseconds < 0) milliseconds = 0;
-    return new TimerImpl(milliseconds, callback);
-  }
+patch Timer _createTimer(Duration duration, void callback()) {
+  int milliseconds = duration.inMilliseconds;
+  if (milliseconds < 0) milliseconds = 0;
+  return new TimerImpl(milliseconds, callback);
+}
 
-  patch factory Timer.periodic(Duration duration, void callback(Timer timer)) {
-    int milliseconds = duration.inMilliseconds;
-    if (milliseconds < 0) milliseconds = 0;
-    return new TimerImpl.periodic(milliseconds, callback);
-  }
+patch Timer _createPeriodicTimer(Duration duration,
+                                 void callback(Timer timer)) {
+  int milliseconds = duration.inMilliseconds;
+  if (milliseconds < 0) milliseconds = 0;
+  return new TimerImpl.periodic(milliseconds, callback);
 }
 
 patch class _AsyncRun {