It doesn't look very good for "native" apps to overscroll when scrolling. Would be nice to have a BrowserWindow option to disable overscroll

![untitled12](https://cloud.githubusercontent.com/assets/170270/15033357/fc36e32e-1293-11e6-8cdc-6c17b0f504dd.gif)
## 
- Electron version: 0.37.8
- Operating system: OS X 10.11.4

atom/browser/web_contents_preferences.cc
double zoom_factor = 1.0;
  if (web_preferences.GetDouble(options::kZoomFactor, &zoom_factor) &&
      zoom_factor != 1.0)
    command_line->AppendSwitchASCII(switches::kZoomFactor,
                                    base::DoubleToString(zoom_factor));
  
  int guest_instance_id;
  if (web_preferences.GetInteger(options::kGuestInstanceID, &guest_instance_id))
    command_line->AppendSwitchASCII(switches::kGuestInstanceID,
                                    base::IntToString(guest_instance_id));
  
  int opener_id;
  if (web_preferences.GetInteger(options::kOpenerID, &opener_id))
    command_line->AppendSwitchASCII(switches::kOpenerID,
                                    base::IntToString(opener_id));
  
  std::string blink_features;
  if (web_preferences.GetString(options::kBlinkFeatures, &blink_features))
    command_line->AppendSwitchASCII(::switches::kEnableBlinkFeatures,
                                    blink_features);
  
  NativeWindow* window = NativeWindow::FromWebContents(web_contents);
  if (window) {
    bool visible = window->IsVisible() && !window->IsMinimized();
    if (!visible)  
      command_line->AppendSwitch("hidden-page");
  }
}
void WebContentsPreferences::OverrideWebkitPrefs(