Fix incorrect use of coords conversion for sticky elements

cc/trees/property_tree.cc

Index: cc/trees/property_tree.cc
diff --git a/cc/trees/property_tree.cc b/cc/trees/property_tree.cc
index f450baa7067a5b3aa83fa9b6f08a201f17eb2e24..78383127b48bd8e2138b6047a60e78b41cdd3140 100644
--- a/cc/trees/property_tree.cc
+++ b/cc/trees/property_tree.cc
@@ -457,8 +457,10 @@ gfx::Vector2dF StickyPositionOffset(TransformTree* tree, TransformNode* node) {
       ancestor_sticky_box_offset + ancestor_containing_block_offset +
       sticky_offset - sticky_box_rect.OffsetFromOrigin();
 
-  return sticky_offset - layer_offset - node->source_to_parent -
-         sticky_box_rect.OffsetFromOrigin();
+  return sticky_offset - layer_offset - sticky_box_rect.OffsetFromOrigin() -
+         ((node->source_node_id != node->parent_id)
+              ? node->source_offset + node->source_to_parent
+              : gfx::Vector2dF());
 }
 
 void TransformTree::UpdateLocalTransform(TransformNode* node) {