* 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 (guest_delegate_)
    guest_delegate_->SetSize(params);
}
bool WebContents::IsGuest() const {
  return type_ == WEB_VIEW;
}
bool WebContents::IsOffScreen() const {
#if defined(ENABLE_OSR)
  return type_ == OFF_SCREEN;
#else
  return false;
#endif
}
void WebContents::OnPaint(const gfx::Rect& dirty_rect, const SkBitmap& bitmap) {
  Emit("paint", dirty_rect, gfx::Image::CreateFrom1xBitmap(bitmap));
}
void WebContents::StartPainting() {
  if (!IsOffScreen())
    return;
#if defined(ENABLE_OSR)
  const auto* wc_impl = static_cast<content::WebContentsImpl*>(web_contents());
  auto* osr_wcv = static_cast<OffScreenWebContentsView*>(wc_impl->GetView());
  if (osr_wcv)
    osr_wcv->SetPainting(true);
#endif
}
void WebContents::StopPainting() {