fix(text): use locale-independent letter case methods (#6016)

[lionel-rowe]

Closes #6016

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.54%. Comparing base (a73ff94) to head (b328479).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6204      +/-   ##
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+ Coverage   96.52%   96.54%   +0.01%     
==========================================
  Files         533      533              
  Lines       40870    40868       -2     
  Branches     6120     6120              
==========================================
+ Hits        39451    39454       +3     
+ Misses       1377     1372       -5     
  Partials       42       42              

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[kt3k]

LGTM

[kt3k]

Could this change/fix any output with Turkish locale?

[lionel-rowe]

Could this change/fix any output with Turkish locale?

@kt3k Sorry, only just noticed this comment after the merge. It would change such output to use "default" letter case conversions (which I think for all intents and purposes is the same as toLocaleXCase('en-US')).

It's possible there could be cases where the locale-sensitive version with the host locale is desirable, but I suspect such cases are rare, as it's usually better to explicitly specify a locale. For example, a Turkish-language-only website should consistently use Turkish letter case conventions even for users' whose browser/OS is in another language; meanwhile, a multilingual website supporting Turkish should use the locale of the current content. In cases where the locale is unknown, perhaps the host locale could be used as a fallback, with the usual caveats about potential bugs (string comparison etc).

[kt3k]

No worries. I agree this is generally a good convention. Thanks for your contribution.

I was just wondering if we should tag this PR refactor if there's no actual fixed case, but that was not a big deal.