Speeding up ElementList.clear & NodeList.clear.

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

Index: tools/dom/templates/html/impl/impl_Node.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Node.darttemplate b/tools/dom/templates/html/impl/impl_Node.darttemplate
index bb01401a69a81c5c22cb4e3d59836ffc5fe6e1d3..a58eefc9d80fdbec9af769720d11edf3c42b8539 100644
--- a/tools/dom/templates/html/impl/impl_Node.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Node.darttemplate
@@ -138,7 +138,7 @@ $endif
   }
 
   void clear() {
-    _this.text = '';
+    _this._clearChildren();
   }
 
   void operator []=(int index, Node value) {
@@ -259,6 +259,12 @@ $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
     }
   }
 
+  void _clearChildren() {
+    while (firstChild != null) {
+      _removeChild(firstChild);
+    }
+  }
+
   /**
    * Print out a String representation of this Node.
    */