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

Source/core/rendering/style/GridResolvedPosition.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/rendering/style/GridResolvedPosition.h"
 
 #include "core/rendering/RenderBox.h"
 #include "core/rendering/style/GridCoordinate.h"
 
@@ skipping 76 matching lines @@
 
 PassOwnPtr<GridSpan> GridResolvedPosition::resolveGridPositionsFromStyle(const RenderStyle& gridContainerStyle, const RenderBox& gridItem, GridTrackSizingDirection direction)
 {
     GridPosition initialPosition, finalPosition;
     initialAndFinalPositionsFromStyle(gridContainerStyle, gridItem, direction, initialPosition, finalPosition);
 
     GridPositionSide initialPositionSide = calculateInitialPositionSide(direction);
     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;
     }
 
     if (initialPosition.shouldBeResolvedAgainstOppositePosition()) {
         // Infer the position from the final position ('auto / 1' or 'span 2 / 3' case).
         GridResolvedPosition finalResolvedPosition = resolveGridPositionFromStyle(gridContainerStyle, finalPosition, finalPositionSide);
         return resolveGridPositionAgainstOppositePosition(gridContainerStyle, finalResolvedPosition, initialPosition, initialPositionSide);
     }
 
@@ skipping 134 matching lines @@
 
     // If there is no named grid line of that name, we resolve the position to 'auto' (which is equivalent to 'span 1' in this case).
     // See http://lists.w3.org/Archives/Public/www-style/2013Jun/0394.html.
     if (it == gridLinesNames.end())
         return GridSpan::create(resolvedOppositePosition, resolvedOppositePosition);
 
     return GridSpan::createWithNamedSpanAgainstOpposite(resolvedOppositePosition, position, side, it->value);
 }
 
 } // namespace blink