Fix more type errors in test scripts.

tools/testing/dart/test_runner.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 executing tests.
  *
  * This module includes:
  * - Managing parallel execution of tests, including timeout checks.
  * - Evaluating the output of each test as pass/fail/crash/timeout.
@@ skipping 1397 matching lines @@
         print("  Error: $e");
         // TODO(ahe): How to report this as a test failure?
         io.exit(1);
         return true;
       });
     }
   }
 
   void _runTest(TestCase test) {
     if (test.usesWebDriver) {
-      browserUsed = test.configuration['browser'];
+      browserUsed = test.configuration['runtime'];
       if (_needsSelenium) _ensureSeleniumServerRunning();
     }
     eventTestAdded(test);
     _tests.add(test);
     _tryRunTest();
   }
 
   /**
    * Monitor the output of the Selenium server, to know when we are ready to
    * begin running tests.
@@ skipping 293 matching lines @@
     }
   }
 
   void eventAllTestsDone() {
     for (var listener in _eventListener) {
       listener.allDone();
     }
   }
 }