Exercise the byte-at-a-time ISO-2022-JP mode escapes (ASCII, JIS-Roman,
half-width katakana, JIS X 0208) and EUC-TW plane-1 plus the 0x8E four-byte
selector. Raises streaming ISO-2022-JP coverage from 54% to 92% and EUC-TW
from 52% to 76%. Output is compared by Unicode scalar to avoid a grapheme
cluster swallowing the trailing sound mark.
