Skip computing param_env and size if not needed

Author: Aaron1011

src/librustc_middle/ty/sty.rs

@@ -2225,4 +2225,3 @@ impl<'tcx> TyS<'tcx> {
         tcx.layout_of(tcx.param_env(did).and(self)).map(|layout| layout.is_zst()).unwrap_or(false)
     }
 }
-