bug(web): differing behavior between .js and .kmx keyboards

Baseline test `k_0201___ralt_2.kmn` has a single rule:

```
group(main) using keys

'c' + [RAlt K_A] > "cd"
```

Typing abcRALT+aabca on a hardware keyboard results in different outputs:

- with a .kmx keyboard (with a desktop engine) the result is `abcdabca`
- however, with a .js keyboard the result is `abcdabcd`.

This is clearly wrong. It could be argued that .js keyboards don't support RALT key (compiler outputs a warning). Therefore #15357 adds another test, `k_0202___alt.kmn` which is identical except that the rule uses ALT instead of RALT:

```
'c' + [Alt K_A] > "cd"
```

With this (and the same input as above) the output is equally wrong: `abcaabca` (instead of `abcdabca`).

(With a .kmx keyboard and the current state of web-core, both keyboards produce the wrong output `abcaabca`, but that's a different bug)