Silence arrow icons in dropdown menus

[atsansone]

From https://buganizer.corp.google.com/issues/337268535

Observed Results

Navigating through the left menu specifically through the lists inside drop downs, I noticed that the arrow icon is announced.

• Screencast VoiceOver
• Screencast ChromeVox

Expected Results

Ensure that the icons that are decorative should not be announced by SR.

User Impact

Screen reader and Cognitive users are not comfortable listening to unnecessary information to them.

Steps to Reproduce

1. Enabled VoiceOver using Command + F5 also ChromeVox using Ctrl + Alt + Z
2. Open the following pages:
   • https://docs.flutter.dev/
   • https://docs.flutter.dev/get-started/install
3. Continue the linear navigation using the Tab key and reach the left menu.
4. Expanded the drop downs and listen to how the displayed list are verbalized by SR.

GAR Assessment

Flutter Docs

GAR Details

1.1. Do all non-text content and user interface components have meaningful accessible names and alternative text?

Environment Details

Machine: MAC/ChromeBook Browser: Chrome Version 120.0.6099.272 (Official Build) (64-bit) Screen reader: VoiceOver / ChromeVox. Bug filling time: 15 mins.