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

tests/isolate/src/Isolate3NegativeTest.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 errors thrown from isolates are
 // processed correctly and don't result in crashes.
 
 #library('Isolate3NegativeTest');
-#import("TestFramework.dart");
+#import('dart:isolate');
+#import('TestFramework.dart');
 
 class TestClass {
   TestClass.named(num this.fld1) : fld2=fld1 {
     TestClass.i = 0;  // Should cause a compilation error.
   }
   num fld1;
   num fld2;
 }
 
 class Isolate3NegativeTest extends Isolate {
@@ skipping 13 matching lines @@
   }
   void spawn_callback(SendPort port) {
     port.call("foo").receive(expect.runs2(msg_callback));
   }
   expect.completes(new Isolate3NegativeTest().spawn()).then(spawn_callback);
 }
 
 main() {
   runTests([test]);
 }