Support subpixel values for text-shadow and box-shadow

Source/core/platform/animation/AnimationUtilities.h

Index: Source/core/platform/animation/AnimationUtilities.h
diff --git a/Source/core/platform/animation/AnimationUtilities.h b/Source/core/platform/animation/AnimationUtilities.h
index 4cdc8291a5e8f3fc7fdc75914b703d0a5db630e0..276f6840e970179638a6020157d61fe0dde7740c 100644
--- a/Source/core/platform/animation/AnimationUtilities.h
+++ b/Source/core/platform/animation/AnimationUtilities.h
@@ -28,6 +28,7 @@
 
 #include "core/platform/LayoutUnit.h"
 #include "core/platform/graphics/IntPoint.h"
+#include "core/platform/graphics/LayoutPoint.h"
 #include "wtf/MathExtras.h"
 
 namespace WebCore {
@@ -62,6 +63,11 @@ inline IntPoint blend(const IntPoint& from, const IntPoint& to, double progress)
     return IntPoint(blend(from.x(), to.x(), progress), blend(from.y(), to.y(), progress));
 }
 
+inline LayoutPoint blend(const LayoutPoint& from, const LayoutPoint& to, double progress)
+{
+    return LayoutPoint(blend(from.x(), to.x(), progress), blend(from.y(), to.y(), progress));
+}
+
 // Calculates the accuracy for evaluating a timing function for an animation with the specified duration.
 inline double accuracyForDuration(double duration)
 {