Don't std::move fTriangleBuffer in tessellation

I forgot that fTriangleBufer can be bound in both the stencil step and
the cover step.

Change-Id: I53a394b37d3d551fe7e1fe25f45d26e7bda46e3a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/305737
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
1 file changed