Added support for isolate unhandled exceptions.

runtime/lib/isolate_patch.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.
 
 patch class ReceivePort {
   /* patch */ factory ReceivePort() {
     return new _ReceivePortImpl();
   }
 }
 
@@ skipping 105 matching lines @@
 
 ReceivePort _portInternal;
 
 patch ReceivePort get port {
   if (_portInternal == null) {
     _portInternal = _getPortInternal();
   }
   return _portInternal;
 }
 
-patch spawnFunction(void topLevelFunction()) native "isolate_spawnFunction";
+patch spawnFunction(void topLevelFunction(),
+    [bool UnhandledExceptionCallback(IsolateUnhandledException e)]) 
+    native "isolate_spawnFunction";
 
-patch spawnUri(String uri) native "isolate_spawnUri";
+patch spawnUri(String uri,
+    [bool UnhandledExceptionCallback(IsolateUnhandledException e)]) 
+    native "isolate_spawnUri";