Auto merge of #33311 - birkenfeld:issue33262, r=nrc

parser: fix suppression of syntax errors in range RHS

Invalid expressions on the RHS were just swallowed without generating an error.  The new version more closely mirrors the code for parsing `..x` in the `parse_prefix_range_expr` method below, where no cancel is done either.

Fixes #33262.

src/test/parse-fail/issue-33262.rs

@@ -0,0 +1,18 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags: -Z parse-only
+
+// Issue #33262
+
+pub fn main() {
+    for i in 0..a as { }
+    //~^ ERROR expected type, found `{`
+}