Execute callbacks from JS in the correct zone

sdk/lib/js/dart2js/js_dart2js.dart

Index: sdk/lib/js/dart2js/js_dart2js.dart
diff --git a/sdk/lib/js/dart2js/js_dart2js.dart b/sdk/lib/js/dart2js/js_dart2js.dart
index 84ec8f356708b114ff9915d2aedadfbc6da46781..4bc28ac2420fd25e47e57a654dff65743a4fec54 100644
--- a/sdk/lib/js/dart2js/js_dart2js.dart
+++ b/sdk/lib/js/dart2js/js_dart2js.dart
@@ -87,6 +87,7 @@
  */
 library dart.js;
 
+import 'dart:async' show Zone;
 import 'dart:html' show Blob, Event, ImageData, Node, Window;
 import 'dart:collection' show HashMap, ListMixin;
 import 'dart:indexed_db' show KeyRange;
@@ -99,22 +100,35 @@ import 'dart:_js_helper' show Primitives, convertDartClosureToJS,
 
 final JsObject context = _wrapToDart(Primitives.computeGlobalThis());
 
-_convertDartFunction(Function f, {bool captureThis: false}) {
+_convertDartFunction(Function f) {
   return JS('',
-    'function(_call, f, captureThis) {'
+    'function(_call, f) {'
       'return function() {'
-        'return _call(f, captureThis, this, '
-            'Array.prototype.slice.apply(arguments));'
+        'return _call(f, Array.prototype.slice.apply(arguments));'
       '}'
-    '}(#, #, #)', DART_CLOSURE_TO_JS(_callDartFunction), f, captureThis);
+    '}(#, #)', DART_CLOSURE_TO_JS(_callDartFunction), _applyZoned(f));
 }
 
-_callDartFunction(callback, bool captureThis, self, List arguments) {
-  if (captureThis) {
-    arguments = [self]..addAll(arguments);
-  }
-  var dartArgs = new List.from(arguments.map(_convertToDart));
-  return _convertToJS(Function.apply(callback, dartArgs));
+_convertDartFunctionWithThis(Function f) {
+  return JS('',
+    'function(_call, f) {'
+      'return function() {'
+        'var args = Array.prototype.slice.apply(arguments);'
+        'args.unshift(this);'
+        'return _call(f, args);'
+      '}'
+    '}(#, #)', DART_CLOSURE_TO_JS(_callDartFunction), _applyZoned(f));
+}
+
+_callDartFunction(f, List arguments) => f(arguments);
+
+_applyZoned(f) {
+  var callDart = (List arguments) {
+    var dartArgs = new List.from(arguments.map(_convertToDart));
+    return _convertToJS(Function.apply(f, dartArgs));
+  };
+  if (Zone.current == Zone.ROOT) return callDart;
+  return Zone.current.bindUnaryCallback(callDart);
 }
 
 /**
@@ -323,7 +337,7 @@ class JsFunction extends JsObject {
    * with the value of this passed as the first argument.
    */
   factory JsFunction.withThis(Function f) {
-    var jsFunc = _convertDartFunction(f, captureThis: true);
+    var jsFunc = _convertDartFunctionWithThis(f);
     return new JsFunction._fromJs(jsFunc);
   }