Allow null to be cast to null.  This fixes a bug where null == null didn't type check.
Allow null to be cast to null.  This fixes a bug where null == null
didn't type check.

liujed/polyglot-eclipse,liujed/polyglot-eclipse,xcv58/polyglot,xcv58/polyglot,blue-systems-group/project.maybe.polyglot,blue-systems-group/project.maybe.polyglot,xcv58/polyglot,liujed/polyglot-eclipse,blue-systems-group/project.maybe.polyglot,liujed/polyglot-eclipse,blue-systems-group/project.maybe.polyglot,xcv58/polyglot