SI-6516, macros comparing types with == instead of =:=.

I gift-wrapped this ticket four months ago:

  'I think it will be enough to say "tpe =:= MacroContextClass.tpe"
   rather than == .'

Indeed. Had to open my own gift. Thanks, paulp!
Merge pull request #2025 from paulp/issue/6516

SI-6516, macros comparing types with == instead of =:=.