Move Iterable implementation to collection.

sdk/lib/_internal/compiler/implementation/scanner/keyword.dart

 // Copyright (c) 2011, 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 scanner;
 
 /**
  * A keyword in the Dart programming language.
  */
-class Keyword extends Iterable<int> implements SourceString {
+class Keyword extends IterableBase<int> implements SourceString {
   static const List<Keyword> values = const <Keyword> [
       const Keyword("assert"),
       const Keyword("break"),
       const Keyword("case"),
       const Keyword("catch"),
       const Keyword("class"),
       const Keyword("const"),
       const Keyword("continue"),
       const Keyword("default"),
       const Keyword("do"),
@@ skipping 201 matching lines @@
  */
 class LeafKeywordState extends KeywordState {
   LeafKeywordState(String syntax) : super(Keyword.keywords[syntax]);
 
   bool isLeaf() => true;
 
   KeywordState next(int c) => null;
 
   String toString() => keyword.syntax;
 }