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

frog/leg/scanner/parser_bench.dart

Index: frog/leg/scanner/parser_bench.dart
diff --git a/frog/leg/scanner/parser_bench.dart b/frog/leg/scanner/parser_bench.dart
index 9a143c968985c27d46be762448f3b07808809396..6c311f9012e63dcef5818ffe211095dea9095251 100644
--- a/frog/leg/scanner/parser_bench.dart
+++ b/frog/leg/scanner/parser_bench.dart
@@ -20,7 +20,7 @@ class ParserBench extends BaseParserBench {
   }
 
   void timedParseAll(List<String> arguments) {
-    StopWatch timer = new StopWatch();
+    Stopwatch timer = new Stopwatch();
     timer.start();
     BenchListener listener = parseAll(arguments);
     timer.stop();