### 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) {
  TRACE_EVENT1("electron", "WebContents::Message", "channel", channel);
   webContents.emit('-ipc-message', new Event(), internal, channel,
   arguments);
  EmitWithSender("-ipc-message", receivers_.current_context(), InvokeCallback(),
                 internal, channel, std::move(arguments));
}
void WebContents::Invoke(bool internal,
                         const std::string& channel,
                         blink::CloneableMessage arguments,
                         InvokeCallback callback) {
  TRACE_EVENT1("electron", "WebContents::Invoke", "channel", channel);
   webContents.emit('-ipc-invoke', new Event(), internal, channel, arguments);
  EmitWithSender("-ipc-invoke", receivers_.current_context(),
                 std::move(callback), internal, channel, std::move(arguments));
}
void WebContents::ReceivePostMessage(const std::string& channel,
                                     blink::TransferableMessage message) {
  v8::Isolate* isolate = JavascriptEnvironment::GetIsolate();
  v8::HandleScope handle_scope(isolate);
  auto wrapped_ports =
      MessagePort::EntanglePorts(isolate, std::move(message.ports));
  v8::Local<v8::Value> message_value =
      electron::DeserializeV8Value(isolate, message);
  EmitWithSender("-ipc-ports", receivers_.current_context(), InvokeCallback(),
                 false, channel, message_value, std::move(wrapped_ports));
}
void WebContents::PostMessage(const std::string& channel,