bug(mac): Keyman for macOS doesn't work in Office Online in Chrome

**Describe the bug**

https://user-images.githubusercontent.com/28331388/162188386-c9c26444-133c-4317-98b7-5555c2ea8cee.mov

Type ស ុ ី (US keys: S U ShiftI) or ស ី ុ (US keys: S ShiftI U) to get the whole word deleted as shown in the screen recording above.

**To Reproduce**

1. Go to 'office online website' (register if you haven't yet)
2. navigate to Word online
3. from the Keyman for macOS app, select Khmer Angkor keyboard (if you haven't had it installed yet, go ahead and do so)
4. In the Word app, type (US keys: S U ShiftI) or ស ី ុ (US keys: S ShiftI U)
5. See error

**Expected behavior**

The expected output is ស៊ី, not nothing.

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**Keyman for macOS:**
- OS: macOS Monterey 12.3.1
- Keyman version: 15.0.224-beta
- Target Application: Word online

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**Keyboard**
- Keyboard name: khmer_angkor
- Keyboard version: 1.3
- Language name: Khmer

**Additional context**

TODO
- Test this same scenario in
- Windows,
- Linux and
- Mobile Web.