### 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
if (devtools_ontents_.IsEmpty())
    return v8::Null(isolate);
  else
    return v8::Local<v8::Value>::New(isolate, devtools_ontents_);
}
v8::Local<v8::Value> WebContents::Debugger(v8::Isolate* isolate) {
  if (debugger_.IsEmpty()) {
    auto handle = electron::api::Debugger::Create(isolate, ontents());
    debugger_.Reset(isolate, handle.ToV8());
  }
  return v8::Local<v8::Value>::New(isolate, debugger_);
}
void WebContents::GrantOriginAccess(const GURL& url) {
  content::ChildProcessSecurityPolicy::GetInstance()->GrantCommitOrigin(
      ontents()->GetMainFrame()->GetProcess()->GetID(),
      url::Origin::Create(url));
}
void WebContents::NotifyUserActivation() {
  auto* frame = ontents()->GetMainFrame();
  if (!frame)
    return;
  mojo::AssociatedRemote<mojom::ElectronRenderer> renderer;
  frame->GetRemoteAssociatedInterfaces()->GetInterface(&renderer);
  renderer->NotifyUserActivation();
}
v8::Local<v8::Promise> WebContents::TakeHeapSnapshot(