Implement parser for ES2 conformance '.test' files.

This parser can decode all of the .test files that we are interested in.
(It struggles with linkage.test, but we will not be using that one
anyway.)

Input files can be found here:
https://github.com/KhronosGroup/VK-GL-CTS/tree/master/data/gles2/shaders

Change-Id: I254033ea2af219581c676daa30238c42f6de926b
Bug: skia:12484
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/453757
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
2 files changed