remove legacy drawPosText (and variants)

Bug: skia:
Change-Id: I112e567d437d729249ceafb500b979ef96e625f9
Reviewed-on: https://skia-review.googlesource.com/c/180924
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
3 files changed