This moves the swizzle domain test into the path used by the DSL so that
the error check benefits both sides. To make this possible we need to
be able to distinguish between equivalent swizzle components like x and
r, so they aren't collapsed down to the same component until the very
end.
Change-Id: I48f2582886391eabd7ce6eae949babdeead6051e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/445280
Reviewed-by: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
b61a243294