Suggest into to convert into isize only if uint is of width 8

Since Into<isize> is not implemented for uint of width greater than 8

Author: samrat

src/librustc_typeck/check/demand.rs

@@ -770,12 +770,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 (&ty::Int(exp), &ty::Uint(found)) => {
                     let is_fallible = match (exp.bit_width(), found.bit_width()) {
                         (Some(exp), Some(found)) if found < exp => false,
-                        (None, Some(found)) if found <= 16 => false,
-                        _ => true
+                        (None, Some(8)) => false,
+                        _ => true,
                     };
                     suggest_to_change_suffix_or_into(err, is_fallible);
                     true
-                },
+                }
                 (&ty::Uint(_), &ty::Int(_)) => {
                     suggest_to_change_suffix_or_into(err, true);
                     true