Fix issue when converting fil->tl.

We should call ResourceTable::getLocales directly,
and not AssetManager::getLocales. The latter will convert
"tl" to "fil" so we'll end up thinking we have resources
for "fil" when we don't really have any.

bug: 15873165

Change-Id: I9753e4608aaecede328a40ee1f3ee6b016d0dedc