Wrap Window in case it's a window from a different page / frame.

lib/html/src/dart2js_Conversions.dart

 // 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.
 
 
 // Conversions for IDBKey.
 //
 // Per http://www.w3.org/TR/IndexedDB/#key-construct
 //
 // "A value is said to be a valid key if it is one of the following types: Array
 // JavaScript objects [ECMA-262], DOMString [WEBIDL], Date [ECMA-262] or float
 // [WEBIDL]. However Arrays are only valid keys if every item in the array is
 // defined and is a valid key (i.e. sparse arrays can not be valid keys) and if
 // the Array doesn't directly or indirectly contain itself. Any non-numeric
 // properties are ignored, and thus does not affect whether the Array is a valid
 // key. Additionally, if the value is of type float, it is only a valid key if
 // it is not NaN, and if the value is of type Date it is only a valid key if its
 // [[PrimitiveValue]] internal property, as defined by [ECMA-262], is not NaN."
 
 // What is required is to ensure that an Lists in the key are actually
 // JavaScript arrays, and any Dates are JavaScript Dates.
 
+// Conversions for Window.  These check if the window is the local
+// window, and if it's not, wraps or unwraps it with a secure wrapper.
+// We need to test for EventTarget here as well as it's a base type.
+// We omit an unwrapper for Window as no methods take a non-local
+// window as a parameter.
+
+Window _convertNativeToDart_Window(win) {
+  return _DOMWindowCrossFrameImpl._createSafe(win);
+}
+
+EventTarget _convertNativeToDart_EventTarget(e) {
+  // Assume it's a Window if it contains the setInterval property.  It may be
+  // from a different frame - without a patched prototype - so we cannot
+  // rely on Dart type checking.
+  if (JS('bool', r'"setInterval" in #', e))
+    return _DOMWindowCrossFrameImpl._createSafe(event);
+  else
+    return e;
+}
+
+EventTarget _convertDartToNative_EventTarget(e) {
+  if (e is _DOMWindowCrossFrameImpl) {
+    return e._window;
+  } else {
+    return e;
+  }
+}
+
 // Conversions for ImageData
 //
 // On Firefox, the returned ImageData is a plain object.
 
 class _TypedImageData implements ImageData {
   final Uint8ClampedArray data;
   final int height;
   final int width;
 
   _TypedImageData(this.data, this.height, this.width);
@@ skipping 370 matching lines @@
 }
 
 
 bool _isJavaScriptDate(value) => JS('bool', '# instanceof Date', value);
 bool _isJavaScriptRegExp(value) => JS('bool', '# instanceof RegExp', value);
 bool _isJavaScriptArray(value) => JS('bool', '# instanceof Array', value);
 bool _isJavaScriptSimpleObject(value) =>
     JS('bool', 'Object.getPrototypeOf(#) === Object.prototype', value);
 bool _isImmutableJavaScriptArray(value) =>
     JS('bool', r'!!(#.immutable$list)', value);