Web Animations: Add a name to AnimationNode and trace running players

Source/core/animation/AnimationNode.h

Index: Source/core/animation/AnimationNode.h
diff --git a/Source/core/animation/AnimationNode.h b/Source/core/animation/AnimationNode.h
index bd8c0f48c2c9c399610437245487e7413457d954..60665100da9598df1ac6b69c5e74f7a4cebec7e3 100644
--- a/Source/core/animation/AnimationNode.h
+++ b/Source/core/animation/AnimationNode.h
@@ -113,6 +113,9 @@ public:
     double localTime(bool& isNull) const { isNull = !m_player; return ensureCalculated().localTime * 1000; }
     double currentIteration(bool& isNull) const { isNull = !ensureCalculated().isInEffect; return ensureCalculated().currentIteration; }
 
+    void setName(const String& name) { m_name = name; }
+    const String& name() const { return m_name; }
+
     virtual void trace(Visitor*);
 
 protected:
@@ -164,6 +167,7 @@ protected:
     } m_calculated;
     mutable bool m_needsUpdate;
     mutable double m_lastUpdateTime;
+    String m_name;
 
     const CalculatedTiming& ensureCalculated() const;
 };