Revert "Fix empty run handling in trivial shaper iterators"

This reverts commit 0f3a26dd1887819c7b813d3af15718be6ed9b714.

Reason for revert: Windows bots are broken

Original change's description:
> Fix empty run handling in trivial shaper iterators
> 
> When the text run is of zero length the iterator starts at the end. The
> trivial itereators did not handle this case.
> 
> Change-Id: Id41304500e33d821874f56ab20085cbc4b2d9b0b
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/252857
> Reviewed-by: Herb Derby <herb@google.com>
> Commit-Queue: Ben Wagner <bungeman@google.com>

TBR=bungeman@google.com,herb@google.com

Change-Id: Ia38e46ac4c04def5d374fbbce450538096d90d64
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/252923
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
2 files changed