Add test of closure vs jump precedence

Author: dtolnay

tests/ui-fulldeps/pprust-parenthesis-insertion.rs

@@ -70,6 +70,9 @@ static EXPRS: &[&str] = &[
     // These mean different things.
     "return - 2",
     "(return) - 2",
+    // Closures and jumps have equal precedence.
+    "|| return break 2",
+    "return break (|| 2)", // FIXME: no parenthesis needed.
     // These mean different things.
     "if let _ = true && false {}",
     "if let _ = (true && false) {}",