* 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
const auto impl = content::RenderWidgetHostImpl::FromID(
      render_view_host->GetProcess()->GetID(),
      render_view_host->GetRoutingID());
  if (impl)
    impl->disable_hidden_ = !background_throttling_;
}
void WebContents::RenderViewDeleted(content::RenderViewHost* render_view_host) {
  Emit("render-view-deleted", render_view_host->GetProcess()->GetID());
}
void WebContents::RenderProcessGone(base::TerminationStatus status) {
  Emit("crashed", status == base::TERMINATION_STATUS_PROCESS_WAS_KILLED);
}
void WebContents::PluginCrashed(const base::FilePath& plugin_path,
                                base::ProcessId plugin_pid) {
  content::WebPluginInfo info;
  auto plugin_service = content::PluginService::GetInstance();
  plugin_service->GetPluginInfoByPath(plugin_path, &info);
  Emit("plugin-crashed", info.name, info.version);
}
void WebContents::MediaStartedPlaying(const MediaPlayerInfo& video_type,
                                      const MediaPlayerId& id) {
  Emit("media-started-playing");
}
void WebContents::MediaStoppedPlaying(const MediaPlayerInfo& video_type,
                                      const MediaPlayerId& id) {
  Emit("media-paused");
}
void WebContents::DidChangeThemeColor(SkColor theme_color) {