Bug 1265806 - Update scrollbar finding code to deal with layer trees on both OS X and Windows properly. r=rbarker

MozReview-Commit-ID: GBC5Y9lLAoL

gfx/layers/apz/src/HitTestingTreeNode.cpp

@@ -123,7 +123,7 @@ HitTestingTreeNode::GetScrollSize() const
 bool
 HitTestingTreeNode::IsScrollbarNode() const
 {
-  return mIsScrollbarContainer;
+  return mIsScrollbarContainer || (mScrollDir != Layer::NONE);
 }
 
 void