fix(web): macOS-Chrome chiral key behavior

[jahorton]

This bug was discovered during testing of #6808 with the "Development Chirality Test Keyboard" found at web/testing/chirality.

Test Results

All tests done on iPad mini 6 running iOS 15.5.

• TEST_CHIRALITY_HARDWARE (FAILED): In Chrome on macOS 12.4, the keycaps shown don't correspond with keys triggered and fired on the hardware keyboard.

Type keys ertyu while holding LAlt on the hardware keyboard, output ´®ʈɥ¨ instead of the expected ɛɽʈɥʊ. See the comparison below.

With	Keys	actual output	screenshot of actual output	expected output
OSK	LAlt + ertyu	ɛɽʈɥʊ		ɛɽʈɥʊ
Hardware	LAlt + ertyu	´®ʈɥ¨		ɛɽʈɥʊ

In Chrome on Windows 10 Pro 21H2, the keycaps shown do correspond with keys triggered and fired on the hardware keyboard.

Failed this test for now as it doesn't work on macOS.

Originally posted by @MakaraSok in https://github.com/keymanapp/keyman/issues/6808#issuecomment-1169689188

Interestingly, the issue doesn't reproduce if you use Chrome on macOS to simulate an iPad; you need to be testing against macOS itself, not Android or iOS.

[mcdurdin]

Note that there is an outstanding design issue around Alt/Option and Ctrl on macOS, not limited to web platform. See #734, #875, #5721.