Migrate convertSwizzle to Swizzle::Make.

There are two forms. Swizzle::Make supports components XYZW only;
Swizzle::MakeWith01 also supports the 01 components, and restructures
the zeros and ones into a constructor (as IRGenerator::convertSwizzle
has historically done). This means that once we are past the initial
IR generation stage, and we know that the 01 components have been
eliminated, we can avoid the extra 01-handling logic and just call
Swizzle::Make directly. This isn't a huge deal but it means that call
sites like the inliner can avoid some extra work that will never happen.

Change-Id: I46690c3d6b07feb6327ee72e8f66f15592a35554
Bug: skia:11342
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/371398
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
20 files changed