use a linked list for GrAtlasTextOp geometries

Instead of using a GrTBlockList<Geometry> to hold the geometries
in the op. Allocate them on the RecordTimeAllocator, and
link them together.

Change-Id: I32af5724e7abeca1ddb6d38b26afbff7919cbc76
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/341725
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
3 files changed