[css-grid] Fix positioned items in grids with implicit tracks

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 1484 matching lines @@
         return;
     }
 
     // For positioned items we cannot use GridSpan::translate(). Because we could end up with negative values, as the positioned items do not create implicit tracks per spec.
     int smallestStart = abs(isForColumns ? m_smallestColumnStart : m_smallestRowStart);
     int resolvedInitialPosition = positions.untranslatedResolvedInitialPosition() + smallestStart;
     int resolvedFinalPosition = positions.untranslatedResolvedFinalPosition() + smallestStart;
 
     GridPosition startPosition = isForColumns ? child.style()->gridColumnStart() : child.style()->gridRowStart();
     GridPosition endPosition = isForColumns ? child.style()->gridColumnEnd() : child.style()->gridRowEnd();
-    int lastExplicitLine = isForColumns ? gridColumnCount() : gridRowCount();
+    int firstExplicitLine = smallestStart;
+    int lastExplicitLine = (isForColumns ? GridResolvedPosition::explicitGridColumnCount(styleRef()) : GridResolvedPosition::explicitGridRowCount(styleRef())) + smallestStart;
 
     bool startIsAuto = startPosition.isAuto()
         || (startPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(startPosition.namedGridLine(), styleRef(), GridResolvedPosition::initialPositionSide(direction)))
-        || (resolvedInitialPosition < 0)
+        || (resolvedInitialPosition < firstExplicitLine)
         || (resolvedInitialPosition > lastExplicitLine);
     bool endIsAuto = endPosition.isAuto()
         || (endPosition.isNamedGridArea() && !GridResolvedPosition::isValidNamedLineOrArea(endPosition.namedGridLine(), styleRef(), GridResolvedPosition::finalPositionSide(direction)))
-        || (resolvedFinalPosition < 0)
+        || (resolvedFinalPosition < firstExplicitLine)
         || (resolvedFinalPosition > lastExplicitLine);
 
     size_t initialPosition = startIsAuto ? 0 : resolvedInitialPosition;
     size_t finalPosition = endIsAuto ? lastExplicitLine : resolvedFinalPosition;
 
     LayoutUnit start = startIsAuto ? LayoutUnit() : isForColumns ?  m_columnPositions[initialPosition] : m_rowPositions[initialPosition];
     LayoutUnit end = endIsAuto ? isForColumns ? logicalWidth() : logicalHeight() : isForColumns ?  m_columnPositions[finalPosition] : m_rowPositions[finalPosition];
 
     breadth = end - start;
 
@@ skipping 547 matching lines @@
 
     return LayoutPoint(rowAxisOffset, columnAxisOffsetForChild(child));
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset) const
 {
     GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink