Added support for isolate unhandled exceptions.

runtime/lib/isolate.cc

 // 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.
 
 #include "platform/assert.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 73 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(parameter);
   {
     // Print the error if there is one.  This may execute dart code to
     // print the exception object, so we need to use a StartIsolateScope.
     StartIsolateScope start_scope(isolate);
     StackZone zone(isolate);
     HandleScope handle_scope(isolate);
     Error& error = Error::Handle();
     error = isolate->object_store()->sticky_error();
     if (!error.IsNull()) {
-      OS::PrintErr("%s\n", error.ToErrorCString());
-      exit(255);
+      OS::PrintErr("in ShutdownIsolate: %s\n", error.ToErrorCString());
     }
   }
   {
     // Shut the isolate down.
     SwitchIsolateScope switch_scope(isolate);
     Dart::ShutdownIsolate();
   }
 }
 
 
@@ skipping 342 matching lines @@
 
 DEFINE_NATIVE_ENTRY(isolate_getPortInternal, 0) {
   const Object& port = Object::Handle(ReceivePortCreate(isolate->main_port()));
   if (port.IsError()) {
     Exceptions::PropagateError(Error::Cast(port));
   }
   return port.raw();
 }
 
 }  // namespace dart