Tooltip erroneously disappears when both selection handles are out of view, and erroneously stays visible when one selection handle is in view.

Steps to Reproduce

1. create a text field
2. highlight enough words to fill the whole text field.
3. Scroll until the tooltip is out of the region but one handle is out of view
4. Scroll until both handles are out of view, but the tooltip is still in view.

class MyApp extends StatelessWidget {
  final textController =
      TextEditingController(text: lorem(words: 100, paragraphs: 4));

  MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
          body: Center(
              child: FractionallySizedBox(
        widthFactor: 0.4,
        child: TextField(
          controller: textController,
        ),
      ))),
    );
  }
}

Expected results:

on step 3: On iOS, it actually seems like when any scrolling is done with the tooltip up, the tooltip closes, regardless of if the region is still in the screen.
on step 4: the tooltip should stay up.

Actual results:

on step 3: the tooltip stays up.

on step 4: the tooltip goes away.

Part of an ongoing fix here: #105799 - just logging this issue for posterities sake.