Remove SkASSERT(fConvexity == kUnknown_Convexity) due to racing

Bug: skia:7822
Change-Id: I2def72a6d032c43376906d189e5ee834c76b0898
Reviewed-on: https://skia-review.googlesource.com/123749
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
Auto-Submit: Yuqian Li <liyuqian@google.com>
1 file changed