Implement H98's 'empty nested contexts' layout rule, i.e., input like
Implement H98's 'empty nested contexts' layout rule, i.e., input
like

x = 2 where

y = 3

is now handled correctly (y will not be sucked into x's "where").

FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs