Remove typestate workaround that's no longer necessary

Author: catamorphism

src/comp/syntax/parse/parser.rs

@@ -1119,11 +1119,8 @@ fn parse_prefix_expr(p: &parser) -> @ast::expr {
     }
     let lo = p.get_lo_pos();
     let hi = p.get_hi_pos();
-    // FIXME: can only remove this sort of thing when both typestate and
-    // alt-exhaustive-match checking are co-operating.
 
-    let lit = @spanned(lo, lo, ast::lit_nil);
-    let ex: ast::expr_ = ast::expr_lit(lit);
+    let ex;
     alt p.peek() {
       token::NOT. {
         p.bump();