Replace run_selenium.py with Dart script that uses the browser controller for performance tests.

samples/third_party/dromaeo/dromaeo_end_condition.js

+// Copyright (c) 2014, 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.
+
+/// File imported by browser_perf_testing.dart controller page to determine when
+/// a performance test is done. This is specific to each performance test.
+
+// The function that does the test to determine if this performance test is
+// completed, given a String containing the event queue (most recent event is
+// last).
+function testIsComplete(message) {
+  return message.indexOf('alldone') != -1;
+}