Web Animations API: Bindings for TimedItem.specified with readonly attributes

Source/core/animation/TimedItem.h

Index: Source/core/animation/TimedItem.h
diff --git a/Source/core/animation/TimedItem.h b/Source/core/animation/TimedItem.h
index deb80fd37c54803eda58e478e36bf69dc085852e..d571a0ad524441705e56127e070e6abd047ec5f5 100644
--- a/Source/core/animation/TimedItem.h
+++ b/Source/core/animation/TimedItem.h
@@ -31,6 +31,7 @@
 #ifndef TimedItem_h
 #define TimedItem_h
 
+#include "core/animation/TimedItemTiming.h"
 #include "core/animation/Timing.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
@@ -82,12 +83,13 @@ public:
     double activeDuration() const;
     double timeFraction() const { return ensureCalculated().timeFraction; }
     double startTime() const { return m_startTime; }
-    double endTime() const { return startTime() + specified().startDelay + activeDuration() + specified().endDelay; }
+    double endTime() const { return startTime() + specifiedTiming().startDelay + activeDuration() + specifiedTiming().endDelay; }
 
     const Player* player() const { return m_player; }
     Player* player() { return m_player; }
     Player* player(bool& isNull) { isNull = !m_player; return m_player; }
-    const Timing& specified() const { return m_specified; }
+    const Timing& specifiedTiming() const { return m_specified; }
+    PassRefPtr<TimedItemTiming> specified() { return TimedItemTiming::create(this); }
 
 protected:
     TimedItem(const Timing&, PassOwnPtr<EventDelegate> = nullptr);