[CSS Grid Layout] Remove stack from grid-auto-flow syntax

Source/core/rendering/RenderGrid.cpp

Index: Source/core/rendering/RenderGrid.cpp
diff --git a/Source/core/rendering/RenderGrid.cpp b/Source/core/rendering/RenderGrid.cpp
index 5221e3ece7743c67a854c39e39114332caa1b9f9..0a50fa3ac28b3e6a304ae47e7f37437d29b9f383 100644
--- a/Source/core/rendering/RenderGrid.cpp
+++ b/Source/core/rendering/RenderGrid.cpp
@@ -194,6 +194,7 @@ public:
 RenderGrid::RenderGrid(Element* element)
     : RenderBlock(element)
     , m_gridIsDirty(true)
+    , m_hasAutoPlacedItems(false)
     , m_orderIterator(this)
 {
     ASSERT(!childrenInline());
@@ -233,9 +234,8 @@ void RenderGrid::addChild(RenderObject* newChild, RenderObject* beforeChild)
     if (newChild->parent() != this)
         return;
 
-    // FIXME: Implement properly "stack" value in auto-placement algorithm.
-    if (!style()->isGridAutoFlowAlgorithmStack()) {
-        // The grid needs to be recomputed as it might contain auto-placed items that will change their position.
+    if (hasAutoPlacedItems()) {
+        // The grid needs to be recomputed as it contains auto-placed items that might change their position.
         dirtyGrid();
         return;
     }
@@ -283,9 +283,8 @@ void RenderGrid::removeChild(RenderObject* child)
 
     ASSERT(child->isBox());
 
-    // FIXME: Implement properly "stack" value in auto-placement algorithm.
-    if (!style()->isGridAutoFlowAlgorithmStack()) {
-        // The grid needs to be recomputed as it might contain auto-placed items that will change their position.
+    if (hasAutoPlacedItems()) {
+        // The grid needs to be recomputed as it contains auto-placed items that will change their position.
         dirtyGrid();
         return;
     }
@@ -917,6 +916,7 @@ void RenderGrid::placeItemsOnGrid()
         OwnPtr<GridSpan> rowPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForRows);
         OwnPtr<GridSpan> columnPositions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), *child, ForColumns);
         if (!rowPositions || !columnPositions) {
+            setHasAutoPlacedItems();
             GridSpan* majorAxisPositions = (autoPlacementMajorAxisDirection() == ForColumns) ? columnPositions.get() : rowPositions.get();
             if (!majorAxisPositions)
                 autoMajorAxisAutoGridItems.append(child);
@@ -930,14 +930,6 @@ void RenderGrid::placeItemsOnGrid()
     ASSERT(gridRowCount() >= GridResolvedPosition::explicitGridRowCount(*style()));
     ASSERT(gridColumnCount() >= GridResolvedPosition::explicitGridColumnCount(*style()));
 
-    // FIXME: Implement properly "stack" value in auto-placement algorithm.
-    if (style()->isGridAutoFlowAlgorithmStack()) {
-        // If we did collect some grid items, they won't be placed thus never laid out.
-        ASSERT(!autoMajorAxisAutoGridItems.size());
-        ASSERT(!specifiedMajorAxisAutoGridItems.size());
-        return;
-    }
-
     placeSpecifiedMajorAxisItemsOnGrid(specifiedMajorAxisAutoGridItems);
     placeAutoMajorAxisItemsOnGrid(autoMajorAxisAutoGridItems);
 
@@ -1093,6 +1085,7 @@ void RenderGrid::dirtyGrid()
     m_grid.resize(0);
     m_gridItemCoordinate.clear();
     m_gridIsDirty = true;
+    m_hasAutoPlacedItems = false;
     m_gridItemsOverflowingGridArea.resize(0);
     m_gridItemsIndexesMap.clear();
 }