Add dart_invoke to tonic for calls into App code.

sky/engine/bindings/dart_callback.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sky/engine/config.h"
 #include "sky/engine/bindings/dart_callback.h"
 
 #include "sky/engine/tonic/dart_converter.h"
 #include "sky/engine/tonic/dart_error.h"
+#include "sky/engine/tonic/dart_invoke.h"
 #include "sky/engine/tonic/dart_state.h"
 
 namespace blink {
 
 DartCallback::DartCallback(DartState* dart_state,
                            Dart_Handle callback,
                            Dart_Handle& exception)
     : callback_(dart_state, callback) {
   if (!Dart_IsClosure(callback)) {
     exception = ToDart("Callback must be a function");
     callback_.Clear();
   }
 }
 
 DartCallback::~DartCallback() {
 }
 
 bool DartCallback::IsIsolateAlive() const {
   return !!callback_.dart_state();
 }
 
 Dart_Isolate DartCallback::GetIsolate() const {
   return callback_.dart_state()->isolate();
 }
 
 bool DartCallback::handleEvent(int argc, Dart_Handle* argv) {
-  LogIfError(Dart_InvokeClosure(callback_.value(), argc, argv));
+  DartInvokeAppClosure(callback_.value(), argc, argv);
   return true;
 }
 
 }  // namespace blink