* Electron version: 1.8.2
* Operating system: macos 10.13.3

Reproducing repo: https://github.com/ibash/electron-webkit-app-drag

Demonstrates a bug where `-webkit-app-region: drag` causes a browser view in front of it to miss click events. Oddly - it does not prevent hover events.

Steps:
1. Clone https://github.com/ibash/electron-webkit-app-drag, `yarn install`, `yarn start`
2. Click "button1"
3. Click "button2"

Expected:

Clicking button1 or button2 pops up an alert: "button clicked!"

Actual:

Only clicking button2 pops up an alert: "button clicked!"

atom/browser/api/atom_api_browser_window.cc
mate::Dictionary web_preferences = mate::Dictionary::CreateEmpty(isolate);
  options.Get(options::kWebPreferences, &web_preferences);
  
  v8::Local<v8::Value> value;
  if (options.Get(options::kBackgroundColor, &value))
    web_preferences.Set(options::kBackgroundColor, value);
  v8::Local<v8::Value> transparent;
  if (options.Get("transparent", &transparent))
    web_preferences.Set("transparent", transparent);
#if defined(ENABLE_OSR)
  
  bool offscreen;
  if (web_preferences.Get("offscreen", &offscreen) && offscreen) {
    auto window_options = const_cast<mate::Dictionary&>(options);
    window_options.Set(options::kFrame, false);
  }
#endif
  if (options.Get("webContents", &web_contents) && !web_contents.IsEmpty()) {