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

gm/SkLinearBitmapPipelineGM.cpp

Index: gm/SkLinearBitmapPipelineGM.cpp
diff --git a/gm/SkLinearBitmapPipelineGM.cpp b/gm/SkLinearBitmapPipelineGM.cpp
index f5e01ca7376dbed96b308b5f18d27351a9bb901a..1bba1c56f92371b3f66ee821c51611b28ecc5943 100644
--- a/gm/SkLinearBitmapPipelineGM.cpp
+++ b/gm/SkLinearBitmapPipelineGM.cpp
@@ -59,7 +59,7 @@ static void draw_rect_orig(SkCanvas* canvas, const SkRect& r, SkColor c, const S
 
     sk_sp<SkImage> image(SkImage::MakeRasterCopy(SkPixmap(info, pmsrc.addr32(), pmsrc.rowBytes())));
     SkPaint paint;
-    int32_t storage[300];
+    int32_t storage[400];
 
     sk_sp<SkShader> shader = image->makeShader(SkShader::kRepeat_TileMode,
                                                SkShader::kRepeat_TileMode);