Bug 1266131 part 2 - [css-grid] Remove unused nsDisplayList::SortByCSSOrder() function. r=dholbert

layout/base/nsDisplayList.cpp

@@ -2158,14 +2158,6 @@ static bool IsContentLEQ(nsDisplayItem* aItem1, nsDisplayItem* aItem2,
   return nsLayoutUtils::CompareTreePosition(content1, content2, commonAncestor) <= 0;
 }
 
-static bool IsCSSOrderLEQ(nsDisplayItem* aItem1, nsDisplayItem* aItem2, void*) {
-  nsIFrame* frame1 = aItem1->Frame();
-  nsIFrame* frame2 = aItem2->Frame();
-  int32_t order1 = frame1 ? frame1->StylePosition()->mOrder : 0;
-  int32_t order2 = frame2 ? frame2->StylePosition()->mOrder : 0;
-  return order1 <= order2;
-}
-
 static bool IsZOrderLEQ(nsDisplayItem* aItem1, nsDisplayItem* aItem2,
                         void* aClosure) {
   {
@@ -2189,10 +2181,6 @@ void nsDisplayList::SortByContentOrder(nsIContent* aCommonAncestor) {
   Sort(IsContentLEQ, aCommonAncestor);
 }
 
-void nsDisplayList::SortByCSSOrder() {
-  Sort(IsCSSOrderLEQ, nullptr);
-}
-
 void nsDisplayList::Sort(SortLEQ aCmp, void* aClosure) {
   ::Sort(this, Count(), aCmp, aClosure);
 }

layout/base/nsDisplayList.h

@@ -2017,13 +2017,6 @@ public:
    * ancestor of some elements, then we lose performance but not correctness
    */
   void SortByContentOrder(nsIContent* aCommonAncestor);
-  /**
-   * Stable sort this list by CSS 'order' property order.
-   * http://dev.w3.org/csswg/css-flexbox-1/#order-property
-   * (also applies to CSS Grid although it's in the Flexbox spec ATM)
-   * It is assumed that the list is already in document content order.
-   */
-  void SortByCSSOrder();
 
   /**
    * Generic stable sort. Take care, because some of the items might be nsDisplayLists