LayoutBox has an updateAfterLayout() method where we do useful post-processing (mostly PaintLayer manipulations).  However, there is not currently an analogous callback for LayoutInline.

It would be very helpful to have an updateAfterLayout() hook for LayoutInline which gets called whenever the inline layout code is finished generating line boxes for the LayoutInline.  At the time that updateAfterLayout() is called, LayoutInline::linesBoundingBox() should have its final value.