Fix ambiguous precedences in UI tests

Author: Urgau

tests/ui/consts/const-err-rpass.rs

@@ -9,7 +9,7 @@ const W: bool = Z <= 'B';
 
 
 fn main() {
-    let _ = ((-1 as i8) << 8 - 1) as f32;
+    let _ = ((-1 as i8) << (8 - 1)) as f32;
     let _ = 0u8 as char;
     let _ = true > false;
     let _ = true >= false;