Revert of Force SkPath::getConvexity() cache for thread safety. (patchset #1 id:1 of https://codereview.chromium.org/2300003003/ )

Reason for revert:
I don't see anything else in the roll that could have caused the diff.

Original issue's description:
> Force SkPath::getConvexity() cache for thread safety.
>
> I happened to stumble on this in a run of TSAN:
>     https://luci-milo.appspot.com/swarming/task/30fffe9497dc6310/steps/dm/0/stdout
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2300003003
>
> Committed: https://skia.googlesource.com/skia/+/d0634eeb565d706df2e148a33f137c6edf42bf2e

TBR=reed@google.com,mtklein@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/2303303002
2 files changed