* Electron version: 1.6.2
* Operating system: macOS 10.12.3 (Sierra)

### Expected behavior

Scrollable elements should bounce (rubber band) when reaching the bounds if a window's `webPreferences.scrollBounce = true`

### Actual behavior

Bouncing does not happen

### How to reproduce

```javascript
var win = new BrowserWindow({
    width:800,
    height:600,
    webPreferences:{
        scrollBounce:true
    }
});
```

atom/renderer/renderer_client_base.cc
blink::WebCustomElement::addEmbedderCustomElementName("webview");
  blink::WebCustomElement::addEmbedderCustomElementName("browserplugin");
  preferences_manager_.reset(new PreferencesManager);
#if defined(OS_WIN)
  
  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
  base::string16 app_id =
      command_line->GetSwitchValueNative(switches::kAppUserModelId);
  if (!app_id.empty()) {
    SetCurrentProcessExplicitAppUserModelID(app_id.c_str());
  }
#endif
#if defined(OS_MACOSX)
  
  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
  if (!command_line->HasSwitch(switches::kScrollBounce)) {
    base::ScopedCFTypeRef<CFStringRef> key(
        base::SysUTF8ToCFStringRef("NSScrollViewRubberbanding"));
    base::ScopedCFTypeRef<CFStringRef> value(
        base::SysUTF8ToCFStringRef("false"));
    CFPreferencesSetAppValue(key, value, kCFPreferencesCurrentApplication);
    CFPreferencesAppSynchronize(kCFPreferencesCurrentApplication);
  }
#endif
}
void RendererClientBase::RenderFrameCreated(