Remove List.copyFrom from VM and from tests. It was removed from the List interface in r941.

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
 class _ChildrenElementList implements ElementList {
   // Raw Element.
   final _ElementImpl _element;
   final _HTMLCollectionImpl _childElements;
@@ skipping 89 matching lines @@
   void addAll(Collection<Element> collection) {
     for (_ElementImpl element in collection) {
       _element.$dom_appendChild(element);
     }
   }
 
   void sort(int compare(Element a, Element b)) {
     throw const UnsupportedOperationException('TODO(jacobr): should we impl?');
   }
 
-  void copyFrom(List<Object> src, int srcStart, int dstStart, int count) {
-    throw 'Not impl yet. todo(jacobr)';
-  }
-
   void setRange(int start, int rangeLength, List from, [int startFrom = 0]) {
     throw const NotImplementedException();
   }
 
   void removeRange(int start, int rangeLength) {
     throw const NotImplementedException();
   }
 
   void insertRange(int start, int rangeLength, [initialValue = null]) {
     throw const NotImplementedException();
@@ skipping 686 matching lines @@
 
   /** @domName Document.createElement */
 $if DART2JS
   // Optimization to improve performance until the dart2js compiler inlines this
   // method.
   factory Element.tag(String tag) native "return document.createElement(tag)";
 $else
   factory Element.tag(String tag) => _document.$dom_createElement(tag);
 $endif
 }