Reland "Remove includes from SkFontTypes.h"

This is a reland of cdd5914dc1918c098d2b53af3f41345ad63730fc

Original change's description:
> Remove includes from SkFontTypes.h
> 
> These aren't needed and at least the comment on the one seems out of
> date.
> 
> Change-Id: If76723b7534b338b4d85b84b7c436bf9659a5f15
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/208666
> Reviewed-by: Mike Klein <mtklein@google.com>
> Commit-Queue: Ben Wagner <bungeman@google.com>

Change-Id: I862910310b95a0c8c1be5187d0a9d27d02e5a761
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/209062
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>