* Electron version: 1.7.6
* Operating system: macOS 10.12, Windows 10

### Expected behavior

Right clicking should open context menu in devtools

### Actual behavior

Right clicking does not open the context menu in devtools

### How to reproduce

- `open Electron.app --args --enable-mixed-sandbox`
- open devtools
- right click in the source tab for example
atom/renderer/atom_sandboxed_renderer_client.cc
v8::Handle<v8::Context> context,
    const std::string& callback_name,
    std::vector<v8::Handle<v8::Value>> args) {
  auto isolate = context->GetIsolate();
  auto binding_key = mate::ConvertToV8(isolate, kIpcKey)->ToString();
  auto private_binding_key = v8::Private::ForApi(isolate, binding_key);
  auto global_object = context->Global();
  v8::Local<v8::Value> value;
  if (!global_object->GetPrivate(context, private_binding_key).ToLocal(&value))
    return;
  if (value.IsEmpty() || !value->IsObject())
    return;
  auto binding = value->ToObject();
  auto callback_key = mate::ConvertToV8(isolate, callback_name)->ToString();
  auto callback_value = binding->Get(callback_key);
  DCHECK(callback_value->IsFunction());  
  auto callback = v8::Handle<v8::Function>::Cast(callback_value);
  ignore_result(callback->Call(context, binding, args.size(), args.data()));
}
}