Rename StopWatch to Stopwatch. Add new Stopwatch.start() and Stopwatch.reset().

corelib/src/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.
 
 /**
- * A simple [StopWatch] interface to measure elapsed time.
+ * A simple [Stopwatch] interface to measure elapsed time.
  */
-interface StopWatch factory StopWatchImplementation {
+interface Stopwatch factory StopwatchImplementation {
 
   /**
-   * Creates a [StopWatch] in stopped state with a zero elapsed count.
+   * Creates a [Stopwatch] in stopped state with a zero elapsed count.
    */
-  StopWatch();
+  Stopwatch();
 
   /**
-   * Starts the [StopWatch]. The [elapsed] count is increasing monotonically.
-   * If the [StopWatch] has been stopped, then calling start again restarts it.
-   * If the [StopWatch] is currently running, then calling start does nothing.
+   * Creates a [Stopwatch] in started state with a zero elapsed count.
+   */
+  Stopwatch.start();
+
+  /**
+   * Starts the [Stopwatch]. The [elapsed] count is increasing monotonically.
+   * If the [Stopwatch] has been stopped, then calling start again restarts it
+   * without resetting the [elapsed] count.
+   * If the [Stopwatch] is currently running, then calling start does nothing.
    */
   void start();
 
   /**
-   * Stops the [StopWatch]. The [elapsed] count stops increasing.
-   * If the [StopWatch] is currently not running, then calling stop does nothing.
+   * Stops the [Stopwatch]. The [elapsed] count stops increasing.
+   * If the [Stopwatch] is currently not running, then calling stop does
+   * nothing.
    */
   void stop();
 
   /**
+   * Resets the [elapsed] count to zero. This method does not stop or start
+   * the [Stopwatch].
+   */
+  void reset();
+
+  /**
    * Returns the elapsed number of clock ticks since calling [start] while the
-   * [StopWatch] is running.
+   * [Stopwatch] is running.
    * Returns the elapsed number of clock ticks between calling [start] and
    * calling [stop].
-   * Returns 0 if the [StopWatch] has never been started.
+   * Returns 0 if the [Stopwatch] has never been started.
    * The elapsed number of clock ticks increases by [frequency] every second.
    */
   int elapsed();
 
   /**
    * Returns the [elapsed] counter converted to microseconds.
    */
   int elapsedInUs();
 
   /**
    * Returns the [elapsed] counter converted to milliseconds.
    */
   int elapsedInMs();
 
   /**
    * Returns the frequency of the elapsed counter in Hz.
    */
   int frequency();
 
 }