Bug 759568 - Part 6. Remove unused nsDisplayList::mVisibleRect; r=jfkthame

MozReview-Commit-ID: 88jIDJ65ALf

layout/base/nsDisplayList.h

@@ -2186,8 +2186,6 @@ private:
   nsDisplayItemLink  mSentinel;
   nsDisplayItemLink* mTop;
 
-  // This is set by ComputeVisibility
-  nsRect mVisibleRect;
   // This is set to true by FrameLayerBuilder if the final visible region
   // is empty (i.e. everything that was visible is covered by some
   // opaque content in this list).