Revert all html warning changes.

tools/dom/templates/html/impl/impl_Window.darttemplate

Index: tools/dom/templates/html/impl/impl_Window.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Window.darttemplate b/tools/dom/templates/html/impl/impl_Window.darttemplate
index cdf44bf52b634cc11e86f6e4bbe3e1453b7c0d58..b84bb5f3fa4760408a3080e9401bbaa9f2f10b8f 100644
--- a/tools/dom/templates/html/impl/impl_Window.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Window.darttemplate
@@ -394,13 +394,4 @@ $endif
   String getEventType(EventTarget target) {
     return _eventType;
   }
-
-  ElementStream<BeforeUnloadEvent> forElement(Element e, {bool useCapture: false}) {
-    return new _ElementEventStreamImpl(e, _eventType, useCapture);
-  }
-
-  ElementStream<BeforeUnloadEvent> _forElementList(ElementList e,
-      {bool useCapture: false}) {
-    return new _ElementListEventStreamImpl(e, _eventType, useCapture);
-  }
 }