* 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_web_contents.cc
if (embedder) {
    NativeWindow* owner_window = nullptr;
    auto relay = NativeWindowRelay::FromWebContents(embedder->web_contents());
    if (relay) {
      owner_window = relay->window.get();
    }
    if (owner_window)
      SetOwnerWindow(owner_window);
    content::RenderWidgetHostView* rwhv =
        web_contents()->GetRenderWidgetHostView();
    if (rwhv) {
      rwhv->Hide();
      rwhv->Show();
    }
  }
}
void WebContents::SetDevToolsWebContents(const WebContents* devtools) {
  if (managed_web_contents())
    managed_web_contents()->SetDevToolsWebContents(devtools->web_contents());
}
v8::Local<v8::Value> WebContents::GetNativeView() const {
  gfx::NativeView ptr = web_contents()->GetNativeView();
  auto buffer = node::Buffer::Copy(
      isolate(), reinterpret_cast<char*>(&ptr), sizeof(gfx::NativeView));
  if (buffer.IsEmpty())
    return v8::Null(isolate());
  else
    return buffer.ToLocalChecked();
}
v8::Local<v8::Value> WebContents::DevToolsWebContents(v8::Isolate* isolate) {