Add clone to Stage. Rename place to mix and PolymorphicUnion to Stage. Cleanup.

src/core/SkBitmapProcShader.h

Index: src/core/SkBitmapProcShader.h
diff --git a/src/core/SkBitmapProcShader.h b/src/core/SkBitmapProcShader.h
index 185a95de66831f3dae430c361232f887e37a8cb2..e2d3900a17a6db64af7f4904217cb0f09c1eebda 100644
--- a/src/core/SkBitmapProcShader.h
+++ b/src/core/SkBitmapProcShader.h
@@ -55,7 +55,7 @@ private:
 // an Sk3DBlitter in SkDraw.cpp
 // Note that some contexts may contain other contexts (e.g. for compose shaders), but we've not
 // yet found a situation where the size below isn't big enough.
-typedef SkSmallAllocator<3, 2100> SkTBlitterAllocator;
+typedef SkSmallAllocator<3, 2400> SkTBlitterAllocator;
 
 // If alloc is non-nullptr, it will be used to allocate the returned SkShader, and MUST outlive
 // the SkShader.