* 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
window_->SetAutoHideMenuBar(auto_hide);
}
bool Window::IsMenuBarAutoHide() {
  return window_->IsMenuBarAutoHide();
}
void Window::SetMenuBarVisibility(bool visible) {
  window_->SetMenuBarVisibility(visible);
}
bool Window::IsMenuBarVisible() {
  return window_->IsMenuBarVisible();
}
#if defined(OS_WIN)
bool Window::HookWindowMessage(UINT message,
                               const MessageCallback& callback) {
  messages_callback_map_[message] = callback;
  return true;
}
void Window::UnhookWindowMessage(UINT message) {
  if (!ContainsKey(messages_callback_map_, message))
    return;
  messages_callback_map_.erase(message);
}
bool Window::IsWindowMessageHooked(UINT message) {
  return ContainsKey(messages_callback_map_, message);
}
void Window::UnhookAllWindowMessages() {
  messages_callback_map_.clear();
}
bool Window::SetThumbnailClip(const gfx::Rect& region) {