### Issue Details

* **Electron Version:**
  * 3.0.x, 4.0.x, 5.0.x, 6.0.x
* **Operating System:**
  * macOS 10.14.5
* **Last Known Working Electron version:**
  * 2.0.x

### Expected Behavior
`BrowserWindow.on('swipe')` fires when doing a 3-finger swipe gesture.

### Actual Behavior
`BrowserWindow.on('swipe')` does not fire.

shell/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 (options.Get("webContents", &web_contents) && !web_contents.IsEmpty()) {
    
    
    
    auto* existing_preferences =
        WebContentsPreferences::From(web_contents->web_contents());
    base::DictionaryValue web_preferences_dict;