Move dromaeo to third_party

client/dom/benchmarks/common/Interval.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 utility object for measuring time intervals.
-
-class Interval {
-  int _start, _stop;
-
-  Interval() {
-  }
-
-  void start() {
-    _start = BenchUtil.now;
-  }
-
-  void stop() {
-    _stop = BenchUtil.now;
-  }
-
-  // Microseconds from between start() and stop().
-  int get elapsedMicrosec() {
-    return (_stop - _start) * 1000;
-  }
-
-  // Milliseconds from between start() and stop().
-  int get elapsedMillisec() {
-    return (_stop - _start);
-  }
-}