Simplify wangs_formula::VectorXform

Adds a SkM44 constructor as well as the existing SkMatrix one.

Only stores the 2x2 matrix as columns instead of caching the swizzles
that might be used. Removes the matrix-type specific branching.

I didn't see any performance difference on motionmark skps on my
machine, so hopefully the bots don't report anything serious and we
can keep the simplification.

Bug: b/238761548, skia:13012
Change-Id: I824283720e722a315859e009d3adf3499c8a80a0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/565337
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
2 files changed