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

public/platform/WebFilterAnimationCurve.h

Index: public/platform/WebFilterAnimationCurve.h
diff --git a/public/platform/WebFilterAnimationCurve.h b/public/platform/WebFilterAnimationCurve.h
index fbacae45814b14402bcdee6ada2e2d8afe9ae6a9..7126a8fd52a11bdf6268aac6e668d3c73f96108a 100644
--- a/public/platform/WebFilterAnimationCurve.h
+++ b/public/platform/WebFilterAnimationCurve.h
@@ -49,6 +49,11 @@ public:
     virtual void add(const WebFilterKeyframe&, double x1, double y1, double x2, double y2) = 0;
     // Adds the keyframe with a steps timing function.
     virtual void add(const WebFilterKeyframe&, 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;

[Nate Chapin, 2015/01/07 19:00:29]

It's kind of unfortunate to have to define these identical functions on 3
different interfaces. I take it that there is a subclass of
WebCompositorAnimationCurve for which these would be nonsensical?

 };
 
 } // namespace blink