### Preflight Checklist
* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details

* **Electron Version:**
  * 10.1.1
* **Operating System:**
  * macOS 10.15.4

We recently started launching as hidden on macOS (that is, `show: false` or `browserWindow.hide()` while loading the page, followed by `browserWindow.show()` when the dock icon is clicked). This results in some busted focus behavior on the first activation of the window. The second activation restores it.

### Expected Behavior
The guest page receives a `focus` event on the first activation of the app, when created with `show: false`.

### Actual Behavior
The guest page doesn't receive the first `focus` event. Subsequent activations do trigger a `focus` event.

### To Reproduce
[Electron Fiddle](https://gist.github.com/CharlieHess/c507468cd40630d04f58c6514100b997)

shell/browser/api/electron_api_web_contents.cc
bool send_to_all,
                                           const std::string& channel,
                                           blink::CloneableMessage args,
                                           int32_t sender_id) {
  std::vector<content::RenderFrameHost*> target_hosts;
  if (!send_to_all) {
    auto* frame_host = ontents()->GetMainFrame();
    if (frame_host) {
      target_hosts.push_back(frame_host);
    }
  } else {
    target_hosts = ontents()->GetAllFrames();
  }
  for (auto* frame_host : target_hosts) {
    mojo::AssociatedRemote<mojom::ElectronRenderer> electron_renderer;
    frame_host->GetRemoteAssociatedInterfaces()->GetInterface(
        &electron_renderer);
    electron_renderer->Message(internal, false, channel, args.ShallowClone(),
                               sender_id);
  }
  return true;
}
bool WebContents::SendIPCMessageToFrame(bool internal,