Added support for isolate unhandled exceptions.

runtime/vm/exceptions.cc

 // 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.
 
 #include "vm/exceptions.h"
 
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/flags.h"
 #include "vm/object.h"
@@ skipping 421 matching lines @@
       class_name = Symbols::New("NullThrownError");
       break;
     case kIllegalJSRegExp:
       library = Library::CoreLibrary();
       class_name = Symbols::New("IllegalJSRegExpException");
       break;
     case kIsolateSpawn:
       library = Library::IsolateLibrary();
       class_name = Symbols::New("IsolateSpawnException");
       break;
+    case kIsolateUnhandledException:
+      library = Library::IsolateLibrary();
+      class_name = Symbols::New("IsolateUnhandledException");
+      break;
   }
 
   return DartLibraryCalls::ExceptionCreate(library, class_name, arguments);
 }
 
 }  // namespace dart