Replace GrColor4h with SkPMColor4f

- Mechanical replacement of GrColor4h (used throughout Ops) with
  SkPMColor4f.
- API adaptation (to/FromGrColor -> to/From_BytesRGBA).
- Complete removal of FromFloats (source was already SkPMColor4f),
  and toFloats (setting uniforms can directly access .vec()).

Bug: skia:
Change-Id: I37eece1fa7ed2545dc6843e840d4cc3c60f19747
Reviewed-on: https://skia-review.googlesource.com/c/166620
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/src/gpu/GrProcessorAnalysis.cpp b/src/gpu/GrProcessorAnalysis.cpp
index 8162131..a22506f 100644
--- a/src/gpu/GrProcessorAnalysis.cpp
+++ b/src/gpu/GrProcessorAnalysis.cpp
@@ -17,10 +17,7 @@
     fIsOpaque = input.isOpaque();
     fUsesLocalCoords = false;
     fProcessorsToEliminate = 0;
-    GrColor4h color;
-    if ((fKnowOutputColor = input.isConstant(&color))) {
-        color.toFloats(fLastKnownOutputColor.vec());
-    }
+    fKnowOutputColor = input.isConstant(&fLastKnownOutputColor);
     for (int i = 0; i < cnt; ++i) {
         if (fUsesLocalCoords && !fKnowOutputColor && !fCompatibleWithCoverageAsAlpha &&
             !fIsOpaque) {