pkg/unittest: Run tests in zones

tools/dom/src/shared_html.dart

Index: tools/dom/src/shared_html.dart
diff --git a/tools/dom/src/shared_html.dart b/tools/dom/src/shared_html.dart
index c44effcaa37d09e80e029cc60c792b340b1df49a..7c4f6960ad009f2bb7ffd1f4ec3e86b2a44a0ac8 100644
--- a/tools/dom/src/shared_html.dart
+++ b/tools/dom/src/shared_html.dart
@@ -4,14 +4,16 @@
 
 part of dart.dom.html;
 
-_wrapZone(callback) {
+_wrapZone(callback(arg)) {
   // For performance reasons avoid wrapping if we are in the root zone.
   if (Zone.current == Zone.ROOT) return callback;
+  if (callback == null) return null;
   return Zone.current.bindUnaryCallback(callback, runGuarded: true);
 }
 
-_wrapBinaryZone(callback) {
+_wrapBinaryZone(callback(arg1, arg2)) {
   if (Zone.current == Zone.ROOT) return callback;
+  if (callback == null) return null;
   return Zone.current.bindBinaryCallback(callback, runGuarded: true);
 }