Speeding up ElementList.clear & NodeList.clear.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 654e26f379abf531b8aa2e650286d21d67322202..5348c39ae06b86eff1c9e8fcad15ae0b172820ac 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -8313,8 +8313,7 @@ class _ChildrenElementList extends ListBase<Element>
   }
 
   void clear() {
-    // It is unclear if we want to keep non element nodes?
-    _element.text = '';
+    _element._clearChildren();
   }
 
   Element removeAt(int index) {
@@ -19667,7 +19666,7 @@ class _ChildNodeListLazy extends ListBase<Node> implements NodeListWrapper {
   }
 
   void clear() {
-    _this.text = '';
+    _this._clearChildren();
   }
 
   void operator []=(int index, Node value) {
@@ -19789,6 +19788,12 @@ class Node extends EventTarget native "Node" {
     }
   }
 
+  void _clearChildren() {
+    while (firstChild != null) {
+      _removeChild(firstChild);
+    }
+  }
+
   /**
    * Print out a String representation of this Node.
    */