Generate stub-generator tests in the build directory, and do not commit them to repository.

tests/stub-generator/src/MintMakerFullyIsolatedTest.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.
 
 // IsolateStubs=MintMakerFullyIsolatedTest.dart:Mint,Purse,PowerfulPurse
 #library("MintMakerFullyIsolatedTest-generatedTest");
-#import("../../isolate/src/TestFramework.dart");
+#import("../../../tests/isolate/src/TestFramework.dart");
 
 interface Purse default PurseImpl{
   Purse();
   int queryBalance();
   Purse$Proxy sproutPurse();
   // The deposit has not completed until the promise completes. If we
   // supported Promise<void> then this could use that.
   Promise<int> deposit(int amount, Purse$Proxy source);
 }
 
@@ skipping 271 matching lines @@
       expect.succeeded();
       print("##DONE##");
     });
   }
 
 }
 
 main() {
   runTests([MintMakerFullyIsolatedTest.testMain]);
 }