[css-grid] Unknown named grid lines on absolutely positioned items

third_party/WebKit/Source/core/layout/LayoutGrid.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1386 matching lines @@
         return;
 
     bool containerHasHorizontalWritingMode = isHorizontalWritingMode();
     for (auto* child : *positionedDescendants) {
         bool hasOrthogonalWritingMode = child->isHorizontalWritingMode() != containerHasHorizontalWritingMode;
         if (hasOrthogonalWritingMode) {
             // FIXME: Properly support orthogonal writing mode.
             continue;
         }
 
-        // FIXME: Detect properly if start/end is auto for inexistent named grid lines.
         LayoutUnit columnOffset = LayoutUnit();
         LayoutUnit columnBreadth = LayoutUnit();
         offsetAndBreadthForPositionedChild(*child, ForColumns, columnOffset, columnBreadth);
         LayoutUnit rowOffset = LayoutUnit();
         LayoutUnit rowBreadth = LayoutUnit();
         offsetAndBreadthForPositionedChild(*child, ForRows, rowOffset, rowBreadth);
 
         child->setOverrideContainingBlockContentLogicalWidth(columnBreadth);
         child->setOverrideContainingBlockContentLogicalHeight(rowBreadth);
         child->setExtraInlineOffset(columnOffset);
         child->setExtraBlockOffset(rowOffset);
     }
 
     LayoutBlock::layoutPositionedObjects(relayoutChildren, info);
 }
 
 void LayoutGrid::offsetAndBreadthForPositionedChild(const LayoutBox& child, GridTrackSizingDirection direction, LayoutUnit& offset, LayoutUnit& breadth)
 {
     ASSERT(child.isHorizontalWritingMode() == isHorizontalWritingMode());
 
     OwnPtr<GridSpan> positions = GridResolvedPosition::resolveGridPositionsFromStyle(*style(), child, direction);
     if (!positions) {
         offset = LayoutUnit();
         breadth = (direction == ForColumns) ? clientLogicalWidth() : clientLogicalHeight();
         return;
     }
 
-    bool startIsAuto = (direction == ForColumns) ? child.style()->gridColumnStart().isAuto() : child.style()->gridRowStart().isAuto();
-    bool endIsAuto = (direction == ForColumns) ? child.style()->gridColumnEnd().isAuto() : child.style()->gridRowEnd().isAuto();
+    GridPosition startPosition = (direction == ForColumns) ? child.style()->gridColumnStart() : child.style()->gridRowStart();
+    GridPosition endPosition = (direction == ForColumns) ? child.style()->gridColumnEnd() : child.style()->gridRowEnd();
+    bool startIsAuto = startPosition.isAuto() || (startPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(startPosition.namedGridLine(), styleRef(), GridResolvedPosition::initialPositionSide(direction)));
+    bool endIsAuto = endPosition.isAuto() || (endPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(endPosition.namedGridLine(), styleRef(), GridResolvedPosition::finalPositionSide(direction)));
 
     GridResolvedPosition firstPosition = GridResolvedPosition(0);
     GridResolvedPosition initialPosition = startIsAuto ? firstPosition : positions->resolvedInitialPosition;
     GridResolvedPosition lastPosition = GridResolvedPosition((direction == ForColumns ? gridColumnCount() : gridRowCount()) - 1);
     GridResolvedPosition finalPosition = endIsAuto ? lastPosition : positions->resolvedFinalPosition;
 
     // Positioned children do not grow the grid, so we need to clamp the positions to avoid ending up outside of it.
     initialPosition = std::min<GridResolvedPosition>(initialPosition, lastPosition);
     finalPosition = std::min<GridResolvedPosition>(finalPosition, lastPosition);
 
@@ skipping 479 matching lines @@
 
     return LayoutPoint(rowAxisOffset, columnAxisOffsetForChild(child));
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink