Support for running a limited amount of browser tests in parallel

tools/test.dart

 #!/usr/bin/env dart
 // Copyright (c) 2012, 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.
 
 /**
  * This file is the entrypoint of the dart test suite.  This suite is used
  * to test:
  *
  *     1. the dart vm
@@ skipping 108 matching lines @@
     });
     if (runningBrowserTests) {
       TestingServerRunner.startHttpServer('127.0.0.1');
       // We start two servers so that we can test cross-domain tests.
       TestingServerRunner.startHttpServer('127.0.0.1',
           allowedPort: TestingServerRunner.serverList[0].port);
     }
   }
 
   var testSuites = new List<TestSuite>();
+  var maxBrowserProcesses = maxProcesses;
   for (var conf in configurations) {
+    // We can't run multiple IE processes in parallel.
+    if (conf['runtime'].startsWith('ie')) {
+      maxBrowserProcesses = 1;
+    }
     TestingServerRunner.setPackageRootDir(conf);
     for (String key in selectors.keys) {
       if (key == 'co19') {
         testSuites.add(new Co19TestSuite(conf));
       } else if (conf['runtime'] == 'vm' && key == 'vm') {
         // vm tests contain both cc tests (added here) and dart tests (added in
         // [TEST_SUITE_DIRECTORIES]).
         testSuites.add(new VMTestSuite(conf));
       } else if (conf['compiler'] == 'dartc' && key == 'dartc') {
         testSuites.add(new SamplesDartcTestSuite(conf));
@@ skipping 11 matching lines @@
     }
   }
 
   void allTestsFinished() {
     TestingServerRunner.terminateHttpServers();
     DebugLogger.close();
   }
 
   // Start process queue.
   new ProcessQueue(maxProcesses,
+                   maxBrowserProcesses,
                    progressIndicator,
                    startTime,
                    printTiming,
                    testSuites,
                    allTestsFinished,
                    verbose,
                    listTests);
 }