Double-and triple-tap to select text broken in Firefox Android

**Describe the bug**
A clear and concise description of what the bug is.
- Which site: dev.phanpy.social
- Which site version: 2024.09.04.74c6bf6
- Which instance: hachyderm.io

**To Reproduce**
Steps to reproduce the behavior:
1. Install Firefox in Android and open it
2. Go to 'https://dev.phanpy.social'
3. Log into your account
4. Tap the "compose" icon
5. Type in a few words
6. Double-tap on a word that you just typed

**Expected behavior**
The word is selected. (Instead, the cursor moves to the spot, but no text is selected.)

**Desktop (please complete the following information):**
- OS: Android
- Browser: Firefox
- Version: 129.0.2

**Smartphone (please complete the following information):**
- Device: Google Pixel 6a
- OS: Android 14
- Browser Firefox
- Version 129.0.2

**Additional context**
Triple-tapping to select a sentence doesn't work either.

(Long-pressing **does** work for word selection, after which you can expand the selected string with the handles.)

I confirmed that it _works_ in Android Chrome, with the same keyboard.

I confirmed that it's _broken_ in Android Firefox whether you're using Phanpy installed as a PWA, or in a browser tab.

Start by reproducing the issue in the compose screen on Firefox Android, then compare double- and triple-tap selection with Android Chrome. Done means selecting a word or sentence works in Firefox Android for both the installed PWA and a browser tab.

Written by the indexing model from the issue text.