Cleanup mdn scripts

client/html/src/DOMWrapperBase.dart

Index: client/html/src/DOMWrapperBase.dart
diff --git a/client/html/src/DOMWrapperBase.dart b/client/html/src/DOMWrapperBase.dart
index 8cf063c3673d8a7c3c2116d549000a1f3bd70b98..bdc2524e5f0d91b8d3c2d313956412cda5fab3e0 100644
--- a/client/html/src/DOMWrapperBase.dart
+++ b/client/html/src/DOMWrapperBase.dart
@@ -7,7 +7,11 @@ class DOMWrapperBase {
 
   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;
   }
 }