Remove GP from drawstate, revision of invariant output for GP

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/c6bc58eded89b0c0a36b8e20e193c200f297a0da

Review URL: https://codereview.chromium.org/791743003
diff --git a/src/effects/SkLightingImageFilter.cpp b/src/effects/SkLightingImageFilter.cpp
index adac45b..e53cb02 100644
--- a/src/effects/SkLightingImageFilter.cpp
+++ b/src/effects/SkLightingImageFilter.cpp
@@ -349,7 +349,7 @@
 
     virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const SK_OVERRIDE {
         // lighting shaders are complicated. We just throw up our hands.
-        inout->mulByUnknownColor();
+        inout->mulByUnknownFourComponents();
     }
 
 private: