* Electron version: 1.6.15
* Operating system: Linux

### Expected behavior

Open a `BrowserWindow` with passed options

### Actual behavior

  - Usually a Segmentation fault.
  - Sometimes `[12843:0100/000000.043847:FATAL:zygote_linux.cc(479)] Failed to synchronise with parent zygote process`
  - Sometimes `[12819:0100/000000.719122:FATAL:zygote_linux.cc(509)] Check failed: len > 0 (0 vs. 0)`

### How to reproduce

I'm still working on making a smaller reproduction case. The issue goes away with small tweaks.

1. Starting from https://github.com/daurnimator/fengari-electron-example
2. Modify main.lua to contain:
```lua
local js = require "js"
local electron = require "electron"

electron.app:on("ready", function()
	local win = js.new(electron.BrowserWindow, js.createproxy({
		backgroundColor = '#2e2c29';
	}, "object"))
	win:loadURL("https://fengari.io")
end)
```

atom/browser/api/atom_api_window.cc
#if defined(OS_WIN)
  std::vector<TaskbarHost::ThumbarButton> buttons;
  if (!args->GetNext(&buttons)) {
    args->ThrowError();
    return false;
  }
  auto window = static_cast<NativeWindowViews*>(window_.get());
  return window->taskbar_host().SetThumbarButtons(
      window_->GetAcceleratedWidget(), buttons);
#else
  return false;
#endif
}
void Window::SetMenu(v8::Isolate* isolate, v8::Local<v8::Value> value) {
  mate::Handle<Menu> menu;
  if (value->IsObject() &&
      mate::V8ToString(value->ToObject()->GetConstructorName()) == "Menu" &&
      mate::ConvertFromV8(isolate, value, &menu)) {
    menu_.Reset(isolate, menu.ToV8());
    window_->SetMenu(menu->model());
  } else if (value->IsNull()) {
    menu_.Reset();
    window_->SetMenu(nullptr);
  } else {
    isolate->ThrowException(v8::Exception::TypeError(
        mate::StringToV8(isolate, "Invalid Menu")));
  }
}
void Window::SetAutoHideMenuBar(bool auto_hide) {