* 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 (type_ == REMOTE)
    return;
  managed_web_contents()->CloseDevTools();
}
bool WebContents::IsDevToolsOpened() {
  if (type_ == REMOTE)
    return false;
  return managed_web_contents()->IsDevToolsViewShowing();
}
bool WebContents::IsDevToolsFocused() {
  if (type_ == REMOTE)
    return false;
  return managed_web_contents()->GetView()->IsDevToolsViewFocused();
}
void WebContents::EnableDeviceEmulation(
    const blink::WebDeviceEmulationParams& params) {
  if (type_ == REMOTE)
    return;
  Send(new ViewMsg_EnableDeviceEmulation(routing_id(), params));
}
void WebContents::DisableDeviceEmulation() {
  if (type_ == REMOTE)
    return;
  Send(new ViewMsg_DisableDeviceEmulation(routing_id()));
}
void WebContents::ToggleDevTools() {