Adding monotonic only API to Blink's animation delegate interface

Source/platform/graphics/GraphicsLayer.cpp

Index: Source/platform/graphics/GraphicsLayer.cpp
diff --git a/Source/platform/graphics/GraphicsLayer.cpp b/Source/platform/graphics/GraphicsLayer.cpp
index 0a8f3ea3bb50d6c4e23b1dd33cb2b58e707ec3b9..04fe0c819146d3d28d7987b39d690be1dbbf0da2 100644
--- a/Source/platform/graphics/GraphicsLayer.cpp
+++ b/Source/platform/graphics/GraphicsLayer.cpp
@@ -1180,13 +1180,13 @@ void GraphicsLayer::paint(GraphicsContext& context, const IntRect& clip)
 }
 
 
-void GraphicsLayer::notifyAnimationStarted(double wallClockTime, double monotonicTime, WebAnimation::TargetProperty)
+void GraphicsLayer::notifyAnimationStarted(double monotonicTime, WebAnimation::TargetProperty)
 {
     if (m_client)
-        m_client->notifyAnimationStarted(this, wallClockTime, monotonicTime);
+        m_client->notifyAnimationStarted(this, monotonicTime);
 }
 
-void GraphicsLayer::notifyAnimationFinished(double, double, WebAnimation::TargetProperty)
+void GraphicsLayer::notifyAnimationFinished(double, WebAnimation::TargetProperty)
 {
     // Do nothing.
 }