direct mask biased to (0,0)

Create mask rectangles in device space.
But, instead of offsetting to the drawing text blob origin
offset to 0,0 to simplify mapping from source space to
device space.

Bug: skia:10251

Change-Id: Ic637eb78879bcfae7e7944053d67d9eaef8490cc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/290133
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
7 files changed