Improve parsing errors and suggestions for bad if statements

src/test/ui/expr/if/if-without-block.rs

@@ -1,9 +1,7 @@
 fn main() {
     let n = 1;
     if 5 == {
-    //~^ NOTE this `if` expression has a condition, but no block
+    //~^ ERROR this `if` expression is missing a block after the condition
         println!("five");
     }
 }
-//~^ ERROR expected `{`, found `}`
-//~| NOTE expected `{`