fix bad counts deserializing SkVertices

Bug: skia:7475
Change-Id: I8064de3f564385f085720772d95934845f3c1dc3
Reviewed-on: https://skia-review.googlesource.com/92741
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed