Add overflow:auto scrollbars to child flex basis.

Source/core/layout/LayoutFlexibleBox.h

 /*
  * Copyright (C) 2011 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 78 matching lines @@
     struct LineContext;
     struct Violation;
 
     // Use an inline capacity of 8, since flexbox containers usually have less than 8 children.
     typedef Vector<LayoutRect, 8> ChildFrameRects;
 
     bool hasOrthogonalFlow(LayoutBox& child) const;
     bool isColumnFlow() const;
     bool isLeftToRightFlow() const;
     bool isMultiline() const;
-    Length flexBasisForChild(LayoutBox& child) const;
+    Length flexBasisForChild(const LayoutBox& child) const;
     LayoutUnit crossAxisExtentForChild(LayoutBox& child) const;
     LayoutUnit crossAxisIntrinsicExtentForChild(LayoutBox& child) const;
     LayoutUnit childIntrinsicHeight(LayoutBox& child) const;
     LayoutUnit childIntrinsicWidth(LayoutBox& child) const;
     LayoutUnit mainAxisExtentForChild(LayoutBox& child) const;
     LayoutUnit crossAxisExtent() const;
     LayoutUnit mainAxisExtent() const;
     LayoutUnit crossAxisContentExtent() const;
     LayoutUnit mainAxisContentExtent(LayoutUnit contentLogicalHeight);
     LayoutUnit computeMainAxisExtentForChild(LayoutBox& child, SizeType, const Length& size);
@@ skipping 15 matching lines @@
     LayoutPoint flowAwareLocationForChild(LayoutBox& child) const;
     // FIXME: Supporting layout deltas.
     void setFlowAwareLocationForChild(LayoutBox& child, const LayoutPoint&);
     void adjustAlignmentForChild(LayoutBox& child, LayoutUnit);
     ItemPosition alignmentForChild(LayoutBox& child) const;
     LayoutUnit mainAxisBorderAndPaddingExtentForChild(LayoutBox& child) const;
     LayoutUnit computeInnerFlexBaseSizeForChild(LayoutBox& child, ChildLayoutType = LayoutIfNeeded);
     bool mainAxisLengthIsDefinite(LayoutBox& child, const Length& flexBasis) const;
     bool childFlexBaseSizeRequiresLayout(LayoutBox& child) const;
     bool needToStretchChildLogicalHeight(LayoutBox& child) const;
+    bool childHasIntrinsicMainAxisSize(const LayoutBox& child) const;
     EOverflow mainAxisOverflowForChild(LayoutBox& child) const;
+    EOverflow crossAxisOverflowForChild(LayoutBox& child) const;
 
     void layoutFlexItems(bool relayoutChildren, SubtreeLayoutScope&);
     LayoutUnit autoMarginOffsetInMainAxis(const OrderedFlexItemList&, LayoutUnit& availableFreeSpace);
     void updateAutoMarginsInMainAxis(LayoutBox& child, LayoutUnit autoMarginOffset);
     bool hasAutoMarginsInCrossAxis(LayoutBox& child) const;
     bool updateAutoMarginsInCrossAxis(LayoutBox& child, LayoutUnit availableAlignmentSpace);
     void repositionLogicalHeightDependentFlexItems(Vector<LineContext>&);
     LayoutUnit clientLogicalBottomAfterRepositioning();
 
     LayoutUnit availableAlignmentSpaceForChild(LayoutUnit lineCrossAxisExtent, LayoutBox& child);
@@ skipping 28 matching lines @@
 
     mutable OrderIterator m_orderIterator;
     int m_numberOfInFlowChildrenOnFirstLine;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutFlexibleBox, isFlexibleBox());
 
 } // namespace blink
 
 #endif // LayoutFlexibleBox_h