Fix more warnings for dart:html.

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

[blois, 2014/02/11 22:48:29]

=> rather than return.

+  }
+
+  ElementStream<BeforeUnloadEvent> _forElementList(ElementList e,
+      {bool useCapture: false}) {
+    return new _ElementListEventStreamImpl(e, _eventType, useCapture);

[blois, 2014/02/11 22:48:29]

ditto.

+  }
 }