Assign correct span to continue expression

Fixes https://github.com/rust-lang/rust/issues/28105.

src/libsyntax/parse/parser.rs

@@ -2142,7 +2142,6 @@ impl<'a> Parser<'a> {
                     return self.parse_loop_expr(None, lo);
                 }
                 if try!(self.eat_keyword(keywords::Continue) ){
-                    let lo = self.span.lo;
                     let ex = if self.token.is_lifetime() {
                         let lifetime = self.get_lifetime();
                         try!(self.bump());

src/test/compile-fail/issue-28105.rs

@@ -0,0 +1,23 @@
+// Copyright 2012-2014 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.
+
+// Make sure that a continue span actually contains the keyword.
+
+fn main() {
+    'a: loop {
+        if false {
+            continue //~ ERROR use of undeclared label
+            'b;
+        } else {
+            break //~ ERROR use of undeclared label
+            'c;
+        }
+    }
+}