Change "typedef" to "class" in core library and related tests.

sdk/lib/collection/list.dart

 // Copyright (c) 2013, 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 dart.collection;
 
 /** A reusable set used to identify cyclic lists during toString() calls. */
 Set _toStringVisiting = new HashSet.identity();
 
 /**
  * Abstract implementation of a list.
  *
  * All operations are defined in terms of `length`, `operator[]`,
  * `operator[]=` and `length=`, which need to be implemented.
  */
-typedef ListBase<E> = Object with ListMixin<E>;
+abstract class ListBase<E> = Object with ListMixin<E>;
 
 /**
  * Base implementation of a [List] class.
  *
  * This class can be used as a mixin.
  *
  * This implements all read operations using only the `length` and
  * `operator[]` members. It implements write operations using those and
  * `length=` and `operator[]=`
  */
@@ skipping 490 matching lines @@
       result.write('[');
       result.writeAll(this, ', ');
       result.write(']');
      } finally {
        _toStringVisiting.remove(this);
      }
 
     return result.toString();
   }
 }