Rename Parser::expected_tokens as Parser::expected_token_types.

Because the `Token` type is similar to but different to the `TokenType`
type, and the difference is important, so we want to avoid confusion.

compiler/rustc_parse/src/parser/expr.rs

@@ -153,7 +153,7 @@ impl<'a> Parser<'a> {
             return Ok((lhs, parsed_something));
         }
 
-        self.expected_tokens.push(TokenType::Operator);
+        self.expected_token_types.push(TokenType::Operator);
         while let Some(op) = self.check_assoc_op() {
             let lhs_span = self.interpolated_or_expr_span(&lhs);
             let cur_op_span = self.token.span;