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

[ermshiperete]

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)