Fixed NullPointerException in Timer.

runtime/tests/dart/src/TimerCancel1Test.dart

Index: runtime/tests/dart/src/TimerCancel1Test.dart
diff --git a/runtime/tests/dart/src/TimerCancel1Test.dart b/runtime/tests/dart/src/TimerCancel1Test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..1065bf346b9c05397fa21f739daee4966d7efa16
--- /dev/null
+++ b/runtime/tests/dart/src/TimerCancel1Test.dart
@@ -0,0 +1,30 @@
+// Copyright (c) 2011, 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.
+
+// Test that a timeout handler can cancel another.
+class TimerCancel1Test {
+  static void testOtherCancel() {
+    var canceleeTimer;
+    var cancelerTimer;
+
+    void timeoutHandlerUnreachable(Timer timer) {
+      Expect.fails("A canceled timeout handler should be unreachable.");
+    }
+
+    void cancelHandler(Timer timer) {
+      canceleeTimer.cancel();
+    }
+
+    canceleeTimer = new Timer(timeoutHandlerUnreachable, 1000, false);
+    cancelerTimer = new Timer(cancelHandler, 1, false);
+  }
+
+  static void testMain() {
+    testOtherCancel();
+  }
+}
+
+main() {
+  TimerCancel1Test.testMain();
+}