Specialize vertex size for GrTextBlob

The old code assumes a conservative size for vertices of 20 bytes,
but this only happens in perspective or strange DFT modes. This can
be reduced to 16 bytes in the non-perspective case a savings of 20%

Change-Id: Ife7e7cc4bd00798f173c5390c3100605908e6276
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/257923
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed