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

Source/core/rendering/style/GridResolvedPosition.cpp

Index: Source/core/rendering/style/GridResolvedPosition.cpp
diff --git a/Source/core/rendering/style/GridResolvedPosition.cpp b/Source/core/rendering/style/GridResolvedPosition.cpp
index dae6429c666d4881df4959fe0c5c63319da2df41..554a38325b5b1fbb0440fd9be78477651927801f 100644
--- a/Source/core/rendering/style/GridResolvedPosition.cpp
+++ b/Source/core/rendering/style/GridResolvedPosition.cpp
@@ -94,10 +94,6 @@ PassOwnPtr<GridSpan> GridResolvedPosition::resolveGridPositionsFromStyle(const R
     GridPositionSide finalPositionSide = calculateFinalPositionSide(direction);
 
     if (initialPosition.shouldBeResolvedAgainstOppositePosition() && finalPosition.shouldBeResolvedAgainstOppositePosition()) {
-        // FIXME: Implement properly "stack" value in auto-placement algorithm.
-        if (gridContainerStyle.isGridAutoFlowAlgorithmStack())
-            return adoptPtr(new GridSpan(0, 0));
-
         // We can't get our grid positions without running the auto placement algorithm.
         return nullptr;
     }