Add DDL to SKPBench

Most of this CL is just repackaging the promise image and tile
code from ViaDDL for reuse by SKPBench.

Change-Id: Ie5003c36fe85cc5be9639552f9488b8e92dcdbbf
Reviewed-on: https://skia-review.googlesource.com/129805
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
9 files changed