Update font whitelists to reflect any changed Firefox default fonts

Masayuki Nakano writes (about Windows fonts):

We decided that we should change our default Japanese fonts from legacy "MS PGothic" (sans-serif) and "MS PMincho" (serif) which have bitmap glyph to modern "Meiryo" or "Yu Gothic" (sans-serif) and "Yu Mincho" (serif).

We should consider updating "font.system.whitelist" to reflect this, although it depends on what fonts are available by default on most Windows systems. We should also check if any other default fonts have been added that we should include in our whitelists.