Moving ListBase, FixedLengthListMixin and UmodifiableListMixin to collection.

tools/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.
 
 part of $LIBRARYNAME;
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
-class _ChildrenElementList implements List {
+class _ChildrenElementList implements List<Element> {
   // Raw Element.
   final Element _element;
   final HtmlCollection _childElements;
 
   _ChildrenElementList._wrap(Element element)
     : _childElements = element.$dom_children,
       _element = element;
 
   List<Element> toList({ bool growable: true }) {
     List<Element> output;
@@ skipping 37 matching lines @@
   bool any(bool f(Element element)) {
     for (Element element in this) {
       if (f(element)) {
         return true;
       }
     }
     return false;
   }
 
   String join([String separator]) {
-    return IterableMixinWorkaround.joinList(this, separator);
+    return _childElements.join(separator);
   }
 
   Iterable map(f(Element element)) {
-    return IterableMixinWorkaround.mapList(this, f);
+    return _childElements.map(f);
   }
 
   Iterable<Element> where(bool f(Element element)) {
-    return IterableMixinWorkaround.where(this, f);
+    return _childElements.where(f);
   }
 
   Iterable expand(Iterable f(Element element)) {
-    return IterableMixinWorkaround.expand(this, f);
+    return _childElements.expand(f);
   }
 
   bool get isEmpty {
     return _element.$dom_firstElementChild == null;
   }
 
   Iterable<Element> take(int n) {
     return IterableMixinWorkaround.takeList(this, n);
   }
 
@@ skipping 1055 matching lines @@
   const ScrollAlignment._internal(this._value);
   toString() => 'ScrollAlignment.$_value';
 
   /// Attempt to align the element to the top of the scrollable area.
   static const TOP = const ScrollAlignment._internal('TOP');
   /// Attempt to center the element in the scrollable area.
   static const CENTER = const ScrollAlignment._internal('CENTER');
   /// Attempt to align the element to the bottom of the scrollable area.
   static const BOTTOM = const ScrollAlignment._internal('BOTTOM');
 }