Animation: Allow CC per-curve timing functions to be steps timing functions

public/platform/WebTransformAnimationCurve.h

Index: public/platform/WebTransformAnimationCurve.h
diff --git a/public/platform/WebTransformAnimationCurve.h b/public/platform/WebTransformAnimationCurve.h
index 072244533dde76c394321c8a32204ddb0d43f869..4aba2820b1e235ff170ed7c0fb9e0fea1b387652 100644
--- a/public/platform/WebTransformAnimationCurve.h
+++ b/public/platform/WebTransformAnimationCurve.h
@@ -44,6 +44,11 @@ public:
     virtual void add(const WebTransformKeyframe&, double x1, double y1, double x2, double y2) = 0;
     // Adds the keyframe with a steps timing function.
     virtual void add(const WebTransformKeyframe&, int steps, float stepsStartOffset) = 0;
+
+    virtual void setLinearTimingFunction() = 0;
+    virtual void setCubicBezierTimingFunction(TimingFunctionType) = 0;
+    virtual void setCubicBezierTimingFunction(double x1, double y1, double x2, double y2) = 0;
+    virtual void setStepsTimingFunction(int numberOfSteps, float stepsStartOffset) = 0;
 };
 
 } // namespace blink