Update Timer API to take the callback as the last parameter.

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 227 matching lines @@
           processDirectory();
         } else {
           // We rely on enqueueing completing asynchronously so use a
           // timer to make it so.
           void enqueueCachedTests(Timer ignore) {
             for (var info in testCache[suiteName]) {
               enqueueTestCaseFromTestInformation(info);
             }
             doDone();
           }
-          new Timer(enqueueCachedTests, 0);
+          new Timer(0, enqueueCachedTests);
         }
       }
     }
 
     // Read test expectations from status files.
     testExpectations = new TestExpectations();
     for (var statusFilePath in statusFilePaths) {
       ReadTestExpectationsInto(testExpectations,
                                '$dartDir/$statusFilePath',
                                configuration,
@@ skipping 690 matching lines @@
 
   void forEachTest(Function onTest,
                    Map testCacheIgnored,
                    String globalTempDir(),
                    [Function onDone = null]) {
     doTest = onTest;
     doDone = (onDone != null) ? onDone : (() => null);
 
     if (configuration['component'] != 'dartc') {
       // Do nothing.  Asynchronously report that the suite is enqueued.
-      new Timer((timerUnused){ doDone(); }, 0);
+      new Timer(0, (timerUnused){ doDone(); });
       return;
     }
     RegExp pattern = configuration['selectors']['dartc'];
     if (!pattern.hasMatch('junit_tests')) {
-      new Timer((timerUnused){ doDone(); }, 0);
+      new Timer(0, (timerUnused){ doDone(); });
       return;
     }
 
     buildDir = TestUtils.buildDir(configuration);
     computeClassPath();
     testClasses = <String>[];
     // Do not read the status file.
     // All exclusions are hardcoded in this script, as they are in testcfg.py.
     processDirectory();
   }
@@ skipping 218 matching lines @@
  * $noCrash tests are expected to be flaky but not crash
  * $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
 """;
     print(report);
    }
 }