CSS Animations: Clamp to avoid underflow when blending unsigned values

Source/core/platform/animation/AnimationUtilities.h

 /*
  * Copyright (C) 2011 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 21 matching lines @@
 
 namespace WebCore {
 
 inline int blend(int from, int to, double progress)
 {
     return lround(from + (to - from) * progress);
 }
 
 inline unsigned blend(unsigned from, unsigned to, double progress)
 {
-    return lround(to > from ? from + (to - from) * progress : from - (from - to) * progress);
+    return clampTo<unsigned>(round(to > from ? from + (to - from) * progress : from - (from - to) * progress));
 }
 
 inline double blend(double from, double to, double progress)
 {
     return from + (to - from) * progress;
 }
 
 inline float blend(float from, float to, double progress)
 {
     return static_cast<float>(from + (to - from) * progress);
@@ skipping 11 matching lines @@
 
 // Calculates the accuracy for evaluating a timing function for an animation with the specified duration.
 inline double accuracyForDuration(double duration)
 {
     return 1.0 / (200.0 * duration);
 }
 
 } // namespace WebCore
 
 #endif // AnimationUtilities_h