Rename RuntimeError to CyclicIntializationError, as per spec.

runtime/tests/vm/dart/isolate_unhandled_exception_test2.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.
 
 library isolate_unhandled_exception_test2;
 
 import 'dart:isolate';
 
 // Tests that an isolate's keeps message handling working after
 // throwing an unhandled exception, if there is a top level callback
 // method that returns whether to continue handling messages or not.
 // This test verifies that a default-named callback function is called
 // when no callback is specified in Isolate.spawnFunction.
 
 // Note: this test will hang if an uncaught exception isn't handled,
 // either by an error in the callback or it returning false.
 
 void entry() {
   port.receive((message, replyTo) {
     if (message == 'throw exception') {
       replyTo.call('throwing exception');
-      throw new RuntimeError('ignore this exception');
+      throw new UnsupportedError('ignore this exception');
     }
     replyTo.call('hello');
     port.close();
   });
 }
 
 bool _unhandledExceptionCallback(IsolateUnhandledException e) {
   return e.source.message == 'ignore this exception';
 }
 
 void main() {
   var isolate_port = spawnFunction(entry);
 
   // Send a message that will cause an ignorable exception to be thrown.
   Future f = isolate_port.call('throw exception');
   f.onComplete((future) {
     // Exception wasn't ignored as it was supposed to be.
     Expect.equals(null, future.exception);
   });
 
   // Verify that isolate can still handle messages.
   isolate_port.call('hi').onComplete((future) {
     Expect.equals(null, future.exception);
     Expect.equals('hello', future.value);
   });
 
 }