add utility for caching char2glyph

Try: out/release/nanobench --match _charToGlyph

Pseudo plan to use this:
- attach to whatever typeface backends need it (probably just freetype)
- have a purge/limiting scheme (e.g. only cache N entries)
- if we care, make the search fancier (e.g. binary, slope, etc.)

Bug: 951647
Change-Id: Ib1042ca5891d2742499faf1314579c402121a855
Reviewed-by: Herb Derby <>
Commit-Queue: Mike Reed <>
6 files changed