The artboard and asset file stems came from unique_file_names, which turned
every character except letters, digits, - and _ into a dash, so the dot of
example.artboard became a dash. Export for Screens now uses a variant that keeps
dots (a name of only dots takes the Artboard-N fallback); safe_file_name still
drops trailing periods and guards device names.
Test: an_artboard_name_keeps_its_dots.
SBaksa
0b3ea7c1d2