Revert "Remove Object.dynamic."

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 298 matching lines @@
     // Browser case:
     // If the browser test failed, it may have been because DumpRenderTree
     // and the virtual framebuffer X server didn't hook up, or DRT crashed with
     // a core dump. Sometimes DRT crashes after it has set the stdout to PASS,
     // so we have to do this check first.
     for (String line in super.stderr) {
       if (line.contains('Gtk-WARNING **: cannot open display: :99') ||
         line.contains('Failed to run command. return code=1')) {
         // If we get the X server error, or DRT crashes with a core dump, retry
         // the test.
-        if ((testCase as Dynamic).numRetries > 0) {
+        if (testCase.dynamic.numRetries > 0) {
           requestRetry = true;
         }
         return true;
       }
     }
 
     // Browser tests fail unless stdout contains
     // 'Content-Type: text/plain' followed by 'PASS'.
     bool has_content_type = false;
     for (String line in super.stdout) {
@@ skipping 214 matching lines @@
     timeoutTimer.cancel();
     if (testCase.output.unexpectedOutput
         && testCase.configuration['verbose'] != null
         && testCase.configuration['verbose']) {
       print(testCase.displayName);
       for (var line in testCase.output.stderr) print(line);
       for (var line in testCase.output.stdout) print(line);
     }
     if (allowRetries && testCase.usesWebDriver
         && testCase.output.unexpectedOutput
-        && (testCase as Dynamic).numRetries > 0) {
+        && testCase.dynamic.numRetries > 0) {
       // Selenium tests can be flaky. Try rerunning.
       testCase.output.requestRetry = true;
     }
     if (testCase.output.requestRetry) {
       testCase.output.requestRetry = false;
       this.timedOut = false;
-      (testCase as Dynamic).numRetries--;
+      testCase.dynamic.numRetries--;
       print("Potential flake. Re-running ${testCase.displayName} "
-          "(${(testCase as Dynamic).numRetries} attempt(s) remains)");
+          "(${testCase.dynamic.numRetries} attempt(s) remains)");
       this.start();
     } else {
       testCase.completed();
     }
   }
 
   /**
    * Process exit handler called at the end of every command. It internally
    * treats all but the last command as compilation steps. The last command is
    * the actual test and its output is analyzed in [testComplete].
@@ skipping 612 matching lines @@
         // the developer doesn't waste his or her time trying to fix a bunch of
         // tests that appear to be broken but were actually just flakes that
         // didn't get retried because there had already been one failure.
         bool allowRetry = _MAX_FAILED_NO_RETRY > _progress.numFailedTests;
         new RunningProcess(test, allowRetry, this).start();
       }
       _numProcesses++;
     }
   }
 }