Use browser_controller instead of selenium in test scripts, by default.

tools/testing/dart/test_suite.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.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 1075 matching lines @@
       // Construct the command that executes the browser test
       do {
         List<Command> commandSet = new List<Command>.from(commands);
 
         var htmlPath_subtest = _createUrlPathFromFile(new Path(htmlPath));
         var fullHtmlPath = _getUriForBrowserTest(info, htmlPath_subtest,
                                                  subtestNames, subtestIndex);
 
         List<String> args = <String>[];
 
-        if (configuration['use_browser_controller']) {
+        if (runtime == "drt") {
+          var dartFlags = [];
+          var contentShellOptions = [];
+
+          contentShellOptions.add('--no-timeout');
+          contentShellOptions.add('--dump-render-tree');
+
+          if (compiler == 'none' || compiler == 'dart2dart') {
+            dartFlags.add('--ignore-unrecognized-flags');
+            if (configuration["checked"]) {
+              dartFlags.add('--enable_asserts');
+              dartFlags.add("--enable_type_checks");
+            }
+            dartFlags.addAll(vmOptions);
+          }
+
+          commandSet.add(CommandBuilder.instance.getContentShellCommand(
+              contentShellFilename, fullHtmlPath, contentShellOptions,
+              dartFlags, configurationDir));
+        } else if (configuration['use_browser_controller']) {
           // This command is not actually run, it is used for reproducing
           // the failure.
           args = ['tools/testing/dart/launch_browser.dart',
                   runtime,
                   fullHtmlPath];
           commandSet.add(CommandBuilder.instance.getBrowserTestCommand(
               runtime, fullHtmlPath, TestUtils.dartTestExecutable.toString(),
               args, configurationDir, checkedMode: configuration['checked']));
-        } else if (TestUtils.usesWebDriver(runtime)) {
+        } else {
+          assert(TestUtils.usesWebDriver(runtime));
           args = [
               dartDir.append('tools/testing/run_selenium.py').toNativePath(),
               '--browser=$runtime',
               // NOTE: This value will be overridden by the test runner
               '--timeout=${configuration['timeout']}',
               '--out=$fullHtmlPath'];
           if (runtime == 'dartium') {
             var dartiumLocation =
                 Locations.getBrowserLocation('dartium', configuration);
             args.add('--executable=$dartiumLocation');
           }
           if (subtestIndex != 0) {
             args.add('--force-refresh');
           }
           commandSet.add(CommandBuilder.instance.getSeleniumTestCommand(
                   runtime, fullHtmlPath, 'python', args, configurationDir));
-        } else {
-          assert(runtime == "drt");
-
-          var dartFlags = [];
-          var contentShellOptions = [];
-
-          contentShellOptions.add('--no-timeout');
-          contentShellOptions.add('--dump-render-tree');
-
-          if (compiler == 'none' || compiler == 'dart2dart') {
-            dartFlags.add('--ignore-unrecognized-flags');
-            if (configuration["checked"]) {
-              dartFlags.add('--enable_asserts');
-              dartFlags.add("--enable_type_checks");
-            }
-            dartFlags.addAll(vmOptions);
-          }
-
-          commandSet.add(CommandBuilder.instance.getContentShellCommand(
-              contentShellFilename, fullHtmlPath, contentShellOptions,
-              dartFlags, configurationDir));
         }
 
         // Create BrowserTestCase and queue it.
         String testDisplayName = '$suiteName/$testName';
         var testCase;
         if (info.optionsFromFile['isMultiHtmlTest']) {
           testDisplayName = '$testDisplayName/${subtestNames[subtestIndex]}';
           testCase = new BrowserTestCase(testDisplayName,
               commandSet, configuration,
               expectations['$testName/${subtestNames[subtestIndex]}'],
@@ skipping 909 matching lines @@
  * $pass tests are expected to pass
  * $failOk tests are expected to fail that we won't fix
  * $fail tests are expected to fail that we should fix
  * $crash tests are expected to crash that we should fix
  * $timeout tests are allowed to timeout
  * $compileErrorSkip tests are skipped on browsers due to compile-time error
 """;
     print(report);
    }
 }