Making all callbacks use zones

tools/dom/templates/html/dartium/html_dartium.darttemplate

Index: tools/dom/templates/html/dartium/html_dartium.darttemplate
diff --git a/tools/dom/templates/html/dartium/html_dartium.darttemplate b/tools/dom/templates/html/dartium/html_dartium.darttemplate
index fdec63380364273d20ad833f1fa6884d5efb2a75..e6e372a1169aa1d739541dac9ef7cc9ef274ace8 100644
--- a/tools/dom/templates/html/dartium/html_dartium.darttemplate
+++ b/tools/dom/templates/html/dartium/html_dartium.darttemplate
@@ -19,7 +19,7 @@
  *
  * * If you've never written a web app before, try our
  * tutorials—[A Game of Darts](http://dartlang.org/docs/tutorials).
- * 
+ *
  * * To see some web-based Dart apps in action and to play with the code,
  * download
  * [Dart Editor](http://www.dartlang.org/#get-started)
@@ -141,3 +141,9 @@ _callPortSync(num id, var message) {
   _callPortLastResult = null;
   return result;
 }
+
+_wrapZone(callback) {
+  // For performance reasons avoid wrapping if we are in the root zone.
+  if (Zone.current == Zone.ROOT) return callback;
+  return Zone.current.bindUnaryCallback(callback, runGuarded: true);
+}