bug(linux): Firefox: extra character inserted when typing in Google doc

### Describe the bug

From the community [site](https://community.software.sil.org/t/myanmar-3-sil-1-7-3-on-ubuntu-22-04-4-google-doc/9101):

> This is what I want to type on Google doc - သေသေချာချာ ကစားလုပ်နော်
>
> ​This is what happens when I use Myanmar 3 (1.7.3) keyboard on Ubuntu 22.04.4 with Keyman for linux while I use Google doc - ေသေ​ေသေချာချာ ကစားလုပ်​ေနော်
>
> I don’t encounter the above problem when I type Burmese using Myanmar 3 (1.7.3) keyboard using Libre Officer Writer.
> Any comment? Help? Fix?

This behavior occurs in Google doc and slide. However, it doesn't occur in Google sheet but the cursor keep jumping around when backspace to delete the characters.

Note: the keyboard works completely fine in Firefox and Text Editor.

### Reproduce the bug

1. Type `abab`
2. Ouput ` ေသေ​ေသေ`
3. Backspace to delete the character but get 2 extra ​ေ before it actually delete the text

### Expected behavior

1. Output `ဘေဘေ`

### Related issues

_No response_

### Keyman apps

- [ ] Keyman for Android
- [ ] Keyman for iPhone and iPad
- [X] Keyman for Linux
- [ ] Keyman for macOS
- [ ] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

17.0.328

### Operating system

Ubuntu 22.04.3

### Device

Windows 11 Home Single Language

### Target application

Google doc, slide and sheet

### Browser

Firefox 130.0 64-bit

### Keyboard name

Myanmar3 (SIL)

### Keyboard version

1.7.3

### Language name

Burmese

### Additional context

_No response_