The current system short circuits out when an SkTextBlob will draw
anything based on its bounds, the bounds of the clip, and the state
of the paint.
A similar thing needs to happen, but the clip needs to be ignored.
Return the nullptr if the SkTextBlob would never draw to signal that
the Slug can be ignored.
Bug: chromium:1277583
Change-Id: I2d6641e03c88ae5f160c479c9e715ad8dc9f65b3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/481592
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
