Revert "Fix a few strong mode errors in dart:html"

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

Index: tools/dom/templates/html/impl/impl_StorageEvent.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_StorageEvent.darttemplate b/tools/dom/templates/html/impl/impl_StorageEvent.darttemplate
index 551e2c7f94cbbcec99fe33a575eab0988131cc82..9d546b330fc4fea4d2110b1ff8cf54567c192adf 100644
--- a/tools/dom/templates/html/impl/impl_StorageEvent.darttemplate
+++ b/tools/dom/templates/html/impl/impl_StorageEvent.darttemplate
@@ -11,7 +11,7 @@ $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS
     {bool canBubble: false, bool cancelable: false, String key, String oldValue,
     String newValue, String url, Storage storageArea}) {
 
-    StorageEvent e = document._createEvent("StorageEvent");
+    var e = document._createEvent("StorageEvent");
     e._initStorageEvent(type, canBubble, cancelable, key, oldValue,
         newValue, url, storageArea);
     return e;