font: add a []byte flavor of string methods.
font: add a []byte flavor of string methods.

Change-Id: I2506067ba6ac12c275b65c3a52cb38579d4b9dca
Reviewed-on: https://go-review.googlesource.com/23464
Reviewed-by: David Crawshaw <a2f0bf29257797dd66800b4fbb9945c3e216c004@golang.org>

golang/image