Properly exposing NodeIterator and TreeWalker.

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

Index: tools/dom/templates/html/impl/impl_TreeWalker.darttemplate
diff --git a/tools/dom/templates/html/dart2js/impl_SpeechRecognition.darttemplate b/tools/dom/templates/html/impl/impl_TreeWalker.darttemplate
similarity index 68%
copy from tools/dom/templates/html/dart2js/impl_SpeechRecognition.darttemplate
copy to tools/dom/templates/html/impl/impl_TreeWalker.darttemplate
index 139f6c5bde6af34c6e477340e6c6ee52331a1477..7bb89a4ead0828247968ff45eab59edcfa0b7656 100644
--- a/tools/dom/templates/html/dart2js/impl_SpeechRecognition.darttemplate
+++ b/tools/dom/templates/html/impl/impl_TreeWalker.darttemplate
@@ -5,9 +5,8 @@
 part of $LIBRARYNAME;
 
 $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
-$!MEMBERS
-  factory SpeechRecognition() {
-    return JS('SpeechRecognition',
-        'new (window.SpeechRecognition || window.webkitSpeechRecognition)()');
+  factory TreeWalker(Node root, int whatToShow) {
+    return document.$dom_createTreeWalker(root, whatToShow, null, false);
   }
+$!MEMBERS
 }