Consolidate some text shadow code.

Source/core/rendering/style/ShadowList.h

Index: Source/core/rendering/style/ShadowList.h
diff --git a/Source/core/rendering/style/ShadowList.h b/Source/core/rendering/style/ShadowList.h
index 6a1a4c1c9ad37d813fbb026dd6f976b874c3667c..dedbbf8d149edb2e00e6317163a96222b5722afb 100644
--- a/Source/core/rendering/style/ShadowList.h
+++ b/Source/core/rendering/style/ShadowList.h
@@ -33,6 +33,8 @@
 
 #include "core/rendering/style/ShadowData.h"
 #include "platform/geometry/LayoutRect.h"
+#include "platform/graphics/DrawLooperBuilder.h"
+#include "wtf/PassOwnPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/Vector.h"
 
@@ -61,6 +63,8 @@ public:
     void adjustRectForShadow(LayoutRect&, float additionalOutlineSize = 0) const;
     void adjustRectForShadow(FloatRect&, float additionalOutlineSize = 0) const;
 
+    PassOwnPtr<DrawLooperBuilder> createDrawLooper(DrawLooperBuilder::ShadowAlphaMode, bool isHorizontal = true) const;
+
 private:
     ShadowList(ShadowDataVector& shadows)
     {