* 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)
  static_cast<NativeWindowViews*>(window_.get())->SetIcon(
      icon->GetHICON(GetSystemMetrics(SM_CXSMICON)),
      icon->GetHICON(GetSystemMetrics(SM_CXICON)));
#elif defined(USE_X11)
  static_cast<NativeWindowViews*>(window_.get())->SetIcon(
      icon->image().AsImageSkia());
#endif
}
#endif
void Window::SetAspectRatio(double aspect_ratio, mate::Arguments* args) {
  gfx::Size extra_size;
  args->GetNext(&extra_size);
  window_->SetAspectRatio(aspect_ratio, extra_size);
}
void Window::PreviewFile(const std::string& path, mate::Arguments* args) {