Remove insertRange.

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

Index: tools/dom/templates/html/impl/impl_Element.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index 57c1d4c0cf015eec1fd96b0382eb23bdf3b7fac0..02ff65f2d26a5e681854247e510eaa53b06cf213 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -192,10 +192,6 @@ class _ChildrenElementList extends ListBase<Element> {
     throw new UnimplementedError();
   }
 
-  void insertRange(int start, int rangeLength, [initialValue = null]) {
-    throw new UnimplementedError();
-  }
-
   Iterable getRange(int start, int end)  {
     throw new UnimplementedError();
   }
@@ -318,10 +314,6 @@ class _FrozenElementList extends ListBase {
     throw new UnsupportedError('');
   }
 
-  void insertRange(int start, int rangeLength, [initialValue = null]) {
-    throw new UnsupportedError('');
-  }
-
   List<Element> sublist(int start, [int end]) {
     return new _FrozenElementList._wrap(_nodeList.sublist(start, end));
   }