[CSS Grid Layout] Implement 'justify-items' parsing

Source/core/rendering/RenderGrid.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 1115 matching lines @@
     case ItemPositionCenter:
         return centeredColumnPositionForChild(child);
     case ItemPositionStart:
         return columnPositionAlignedWithGridContainerStart(child);
     case ItemPositionEnd:
         return columnPositionAlignedWithGridContainerEnd(child);
 
     case ItemPositionAuto:
     case ItemPositionStretch:
     case ItemPositionBaseline:
+    case ItemPositionLastBaseline:
         // FIXME: Implement the previous values. For now, we always start align the child.
         return startOfColumnForChild(child);
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 LayoutUnit RenderGrid::rowPositionForChild(const RenderBox* child) const
 {
@@ skipping 89 matching lines @@
     if (isOutOfFlowPositioned())
         return "RenderGrid (positioned)";
     if (isAnonymous())
         return "RenderGrid (generated)";
     if (isRelPositioned())
         return "RenderGrid (relative positioned)";
     return "RenderGrid";
 }
 
 } // namespace WebCore