### 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
const std::string& channel,
                              blink::CloneableMessage arguments,
                              MessageSyncCallback callback) {
  TRACE_EVENT1("electron", "WebContents::MessageSync", "channel", channel);
   webContents.emit('-ipc-message-sync', new Event(sender, message), internal,
   channel, arguments);
  EmitWithSender("-ipc-message-sync", receivers_.current_context(),
                 std::move(callback), internal, channel, std::move(arguments));
}
void WebContents::MessageTo(bool internal,
                            bool send_to_all,
                            int32_t ontents_id,
                            const std::string& channel,
                            blink::CloneableMessage arguments) {
  TRACE_EVENT1("electron", "WebContents::MessageTo", "channel", channel);
  auto* ontents = FromID(ontents_id);
  if (ontents) {
    ontents->SendIPCMessageWithSender(internal, send_to_all, channel,
                                           std::move(arguments), ID());
  }
}
void WebContents::MessageHost(const std::string& channel,