### 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
content::WebContents* source,
    std::unique_ptr<content::WebContents> new_contents,
    const GURL& target_url,
    WindowOpenDisposition disposition,
    const gfx::Rect& initial_rect,
    bool user_gesture,
    bool* was_blocked) {
  auto* tracker = ChildWebContentsTracker::FromWebContents(new_contents.get());
  DCHECK(tracker);
  v8::Isolate* isolate = JavascriptEnvironment::GetIsolate();
  v8::Locker locker(isolate);
  v8::HandleScope handle_scope(isolate);
  auto api_ontents =
      CreateAndTake(isolate, std::move(new_contents), Type::BROWSER_WINDOW);
  if (Emit("-add-new-contents", api_ontents, disposition, user_gesture,
           initial_rect.x(), initial_rect.y(), initial_rect.width(),
           initial_rect.height(), tracker->url, tracker->frame_name,
           tracker->referrer, tracker->raw_features, tracker->body)) {
    
    api_ontents->DestroyWebContents(true );
  }
}
content::WebConbContents::OpenURLFromTab(