Fix some warnings.

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 93 matching lines @@
   }
 
   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 length, List from, [int startFrom = 0]) {
+  void setRange(int start, int rangeLength, List from, [int startFrom = 0]) {
     throw const NotImplementedException();
   }
 
-  void removeRange(int start, int length) {
+  void removeRange(int start, int rangeLength) {
     throw const NotImplementedException();
   }
 
-  void insertRange(int start, int length, [initialValue = null]) {
+  void insertRange(int start, int rangeLength, [initialValue = null]) {
     throw const NotImplementedException();
   }
 
-  List getRange(int start, int length) =>
-    new _FrozenElementList._wrap(_Lists.getRange(this, start, length,
+  List getRange(int start, int rangeLength) =>
+    new _FrozenElementList._wrap(_Lists.getRange(this, start, rangeLength,
         <Element>[]));
 
   int indexOf(Element element, [int start = 0]) {
     return _Lists.indexOf(this, element, start, this.length);
   }
 
   int lastIndexOf(Element element, [int start = null]) {
     if (start === null) start = length - 1;
     return _Lists.lastIndexOf(this, element, start);
   }
 
   void clear() {
     // It is unclear if we want to keep non element nodes?
     _element.text = '';
   }
 
   Element removeLast() {
-    final last = this.last();
-    if (last != null) {
-      _element.$dom_removeChild(last);
+    final result = this.last();
+    if (result != null) {
+      _element.$dom_removeChild(result);
     }
-    return last;
+    return result;
   }
 
   Element last() {
     return _element.$dom_lastElementChild;
   }
 }
 
 // TODO(jacobr): this is an inefficient implementation but it is hard to see
 // a better option given that we cannot quite force NodeList to be an
 // ElementList as there are valid cases where a NodeList JavaScript object
@@ skipping 72 matching lines @@
   Iterator<Element> iterator() => new _FrozenElementListIterator(this);
 
   void addAll(Collection<Element> collection) {
     throw const UnsupportedOperationException('');
   }
 
   void sort(int compare(Element a, Element b)) {
     throw const UnsupportedOperationException('');
   }
 
-  void setRange(int start, int length, List from, [int startFrom = 0]) {
+  void setRange(int start, int rangeLength, List from, [int startFrom = 0]) {
     throw const UnsupportedOperationException('');
   }
 
-  void removeRange(int start, int length) {
+  void removeRange(int start, int rangeLength) {
     throw const UnsupportedOperationException('');
   }
 
-  void insertRange(int start, int length, [initialValue = null]) {
+  void insertRange(int start, int rangeLength, [initialValue = null]) {
     throw const UnsupportedOperationException('');
   }
 
-  ElementList getRange(int start, int length) =>
-    new _FrozenElementList._wrap(_nodeList.getRange(start, length));
+  ElementList getRange(int start, int rangeLength) =>
+    new _FrozenElementList._wrap(_nodeList.getRange(start, rangeLength));
 
   int indexOf(Element element, [int start = 0]) =>
     _nodeList.indexOf(element, start);
 
   int lastIndexOf(Element element, [int start = null]) =>
     _nodeList.lastIndexOf(element, start);
 
   void clear() {
     throw const UnsupportedOperationException('');
   }
@@ skipping 28 matching lines @@
    */
   bool hasNext() => _index < _list.length;
 }
 
 class _ElementList extends _ListWrapper<Element> implements ElementList {
   _ElementList(List<Element> list) : super(list);
 
   ElementList filter(bool f(Element element)) =>
     new _ElementList(super.filter(f));
 
-  ElementList getRange(int start, int length) =>
-    new _ElementList(super.getRange(start, length));
+  ElementList getRange(int start, int rangeLength) =>
+    new _ElementList(super.getRange(start, rangeLength));
 }
 
 class _ElementAttributeMap implements AttributeMap {
 
   final _ElementImpl _element;
 
   _ElementAttributeMap(this._element);
 
   bool containsValue(String value) {
     final attributes = _element.$dom_attributes;
@@ skipping 456 matching lines @@
 
   /** @domName Document.createElement */
 $if FROG
   // Optimization to improve performance until the frog 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
 }