The suggested TODO is no longer deemed necessary (and is too
expensive to do for all LocaleLists). LocaleLists get (and will get)
passed down to the native level through strings that are the result
of calls to toLanguageTags(), which is pre-computed at construction
time. Users who need to interact with the native level can do their
own caching, such as in commit
cfc607cf57.
Change-Id: I665f3b28eaf8df309bf1aec96f9d237aeb72865c
8076c3a685