* 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
CommonWebContentsDelegate::ExitFullscreenModeForTab(source);
  Emit("leave-html-full-screen");
}
void WebContents::RendererUnresponsive(
    content::WebContents* source,
    const content::WebContentsUnresponsiveState& unresponsive_state) {
  Emit("unresponsive");
  if ((type_ == BROWSER_WINDOW || type_ == OFF_SCREEN) && owner_window())
    owner_window()->RendererUnresponsive(source);
}
void WebContents::RendererResponsive(content::WebContents* source) {
  Emit("responsive");
  if ((type_ == BROWSER_WINDOW || type_ == OFF_SCREEN) && owner_window())
    owner_window()->RendererResponsive(source);
}
bool WebContents::HandleContextMenu(const content::ContextMenuParams& params) {
  if (params.custom_context.is_pepper_menu) {
    Emit("pepper-context-menu",
         std::make_pair(params, web_contents()),
         base::Bind(&content::WebContents::NotifyContextMenuClosed,
                    base::Unretained(web_contents()), params.custom_context));
  } else {
    Emit("context-menu", std::make_pair(params, web_contents()));
  }
  return true;
}
bool WebContents::OnGoToEntryOffset(int offset) {