* 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
bool explicit_set) {
  auto title = entry ? entry->GetTitle() : base::string16();
  Emit("page-title-updated", title, explicit_set);
}
void WebContents::DidUpdateFaviconURL(
    const std::vector<content::FaviconURL>& urls) {
  std::set<GURL> unique_urls;
  for (const auto& iter : urls) {
    if (iter.icon_type != content::FaviconURL::IconType::kFavicon)
      continue;
    const GURL& url = iter.icon_url;
    if (url.is_valid())
      unique_urls.insert(url);
  }
  Emit("page-favicon-updated", unique_urls);
}
void WebContents::DevToolsReloadPage() {