Fix some bad documentation links.

sdk/lib/core/stopwatch.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 dart.core;
 
 /**
  * A simple stopwatch interface to measure elapsed time.
  */
 class Stopwatch {
@@ skipping 94 matching lines @@
   }
 
   /**
    * The [elapsedTicks] counter converted to milliseconds.
    */
   int get elapsedMilliseconds {
     return (elapsedTicks * 1000) ~/ frequency;
   }
 
   /**
-   * Whether the [StopWatch] is currently running.
+   * Whether the [Stopwatch] is currently running.
    */
   bool get isRunning => _stop == null;
 
   /**
    * Initializes the time-measuring system. *Must* initialize the [_frequency]
    * variable.
    */
   external static void _initTicker();
   external static int _now();
 }