* Electron Version: 3.0.0-beta1
* Operating System (Platform and Version): macOS
* Last known working Electron version: 2.0.2

**Expected Behavior**
```css
html, body, * {
    -webkit-app-region: drag;
    -webkit-user-select: none;
    cursor: default;
}
```
should allow users to move the position of the window by dragging it directly.

**Actual behavior**
The window is not draggable.
The `cursor` and `-webkit-user-select` properties work well.

**To Reproduce**
copy the CSS above, paste it into a frameless app's `<style>` tag, and run the app.

**Screenshots**

**Additional Information**

atom/browser/api/atom_api_browser_window.cc
content::RenderFrameHost* rfh) {
  bool handled = true;
  IPC_BEGIN_MESSAGE_MAP_WITH_PARAM(BrowserWindow, message, rfh)
    IPC_MESSAGE_HANDLER(AtomFrameHostMsg_UpdateDraggableRegions,
                        UpdateDraggableRegions)
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP()
  return handled;
}
void BrowserWindow::OnCloseContents() {
  DCHECK(web_contents());
  
  v8::Locker locker(isolate());
  v8::HandleScope handle_scope(isolate());
  for (v8::Local<v8::Value> value : child_windows_.Values(isolate())) {
    mate::Handle<BrowserWindow> child;
    if (mate::ConvertFromV8(isolate(), value, &child) && !child.IsEmpty())
      child->window()->CloseImmediately();
  }
  
  
  
  
  
  window()->CloseImmediately();
  
  window_unresponsive_closure_.Cancel();
}
void BrowserWindow::OnRendererResponsive() {