isolates refactor: this change introduces 'dart:isolate' as a library. This is a

tests/isolate/src/IsolateNegativeTest.dart

 // 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.
 
 // Dart test program for testing that isolates are spawned.
 
 #library('IsolateNegativeTest');
-#import("TestFramework.dart");
+#import('dart:isolate');
+#import('TestFramework.dart');
 
 class IsolateNegativeTest extends Isolate {
   IsolateNegativeTest() : super();
 
   void main() {
     this.port.receive((ignored, replyTo) {
       replyTo.send("foo", null);
     });
   }
 }
 
 void test(TestExpectation expect) {
   expect.completes(new IsolateNegativeTest().spawn()).then((SendPort port) {
     port.call("foo").receive(expect.runs2((message, replyTo) {
       Expect.equals(true, "Expected fail");   // <=-------- Should fail here.
       expect.succeeded();
     }));
   });
 }
 
 main() {
   runTests([test]);
 }