Re-enable the nonsquare matrix test.

The mat4x2 portion of the test no longer checks its results, as there
are bugs in the Intel and Radeon GPU drivers that prevent mat4x2s
from being constructed properly.

The SkSL optimizer ends up eliminating the 4x2 matrix entirely because
it is unused by the rest of the code, as well at the 4x4 matrix which is
calculated from the 4x2. At this point, I'm OK with this.

Change-Id: If1464f9e4938b0a37b2ec180c686972389d94e83
Bug: skia:12003
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/408900
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
7 files changed