[CSS Grid Layout] Adapting align-self, align-items and justify-self to the last CSS 3 spec.

Source/core/rendering/style/RenderStyle.h

Index: Source/core/rendering/style/RenderStyle.h
diff --git a/Source/core/rendering/style/RenderStyle.h b/Source/core/rendering/style/RenderStyle.h
index 9bb1aae8b6a2bd6877862a2530c90609b76aee90..47134b3798f3d4e2c2f37bb3d1a122bb9715192d 100644
--- a/Source/core/rendering/style/RenderStyle.h
+++ b/Source/core/rendering/style/RenderStyle.h
@@ -1533,6 +1533,11 @@ public:
 
     bool hasBoxDecorations() const { return hasBorder() || hasBorderRadius() || hasOutline() || hasAppearance() || boxShadow() || hasFilter(); }
 
+    void resolveJustifyItemsAuto(const RenderStyle&);
+    void resolveJustifySelfAuto(const RenderStyle&);
+    void resolveAlignItemsAuto(const RenderStyle&);
+    void resolveAlignSelfAuto(const RenderStyle&);
+
     // Initial values for all the properties
     static EBorderCollapse initialBorderCollapse() { return BSEPARATE; }
     static EBorderStyle initialBorderStyle() { return BNONE; }
@@ -1608,7 +1613,7 @@ public:
     static Length initialFlexBasis() { return Length(Auto); }
     static int initialOrder() { return 0; }
     static EAlignContent initialAlignContent() { return AlignContentStretch; }
-    static ItemPosition initialAlignItems() { return ItemPositionStretch; }
+    static ItemPosition initialAlignItems() { return ItemPositionAuto; }
     static OverflowAlignment initialAlignItemsOverflowAlignment() { return OverflowAlignmentDefault; }
     static ItemPosition initialAlignSelf() { return ItemPositionAuto; }
     static OverflowAlignment initialAlignSelfOverflowAlignment() { return OverflowAlignmentDefault; }