Cleanup mdn scripts

client/html/src/DOMWrapperBase.dart

 // Copyright (c) 2011, 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.
 
 class DOMWrapperBase {
   final _ptr;
 
   DOMWrapperBase._wrap(this._ptr) {
         // We should never be creating duplicate wrappers.
-        assert(_ptr.dartObjectLocalStorage === null);
+        // TODO(jacobr): this boolean value is evaluated outside of the assert
+        // to work around a mysterious and flaky bug in tip of trunk versions of
+        // chrome.
+        bool hasExistingWrapper = _ptr.dartObjectLocalStorage === null;
+        assert(hasExistingWrapper);
         _ptr.dartObjectLocalStorage = this;
   }
 }
 
 /** This function is provided for unittest purposes only. */
 unwrapDomObject(DOMWrapperBase wrapper) {
   return wrapper._ptr;
 }