Support subpixel values for text-shadow and box-shadow

Source/platform/animation/AnimationUtilities.h

Index: Source/platform/animation/AnimationUtilities.h
diff --git a/Source/platform/animation/AnimationUtilities.h b/Source/platform/animation/AnimationUtilities.h
index 9b92bd0b864d9e1748896c326be2cc0d25b0a522..81a8a73f5a2dc03230b85e1ec0d82928e11c9220 100644
--- a/Source/platform/animation/AnimationUtilities.h
+++ b/Source/platform/animation/AnimationUtilities.h
@@ -28,6 +28,7 @@
 
 #include "platform/LayoutUnit.h"
 #include "platform/PlatformExport.h"
+#include "platform/geometry/FloatPoint.h"
 #include "platform/geometry/IntPoint.h"
 #include "wtf/MathExtras.h"
 #include "wtf/TypeTraits.h"
@@ -67,6 +68,11 @@ 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 FloatPoint blend(const FloatPoint& from, const FloatPoint& to, double progress)
+{
+    return FloatPoint(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)
 {