Delete GrSTArenaList

The intent of this class was to abstract the internal linked list used
by GrStrokeTessellateOp, but it seems to just make things more
complicated. We have a need now to iterate the list with more freedom
than is offered by GrSTArenaList, so it seems best to just use a plain
C-style linked list instead.

Bug: chromium:1172543
Change-Id: Ia76be83c523bd3c285200099a529ccd3818490b6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/372656
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
10 files changed