Don't peek when parsing mixin applications.

pkg/front_end/lib/src/incremental/unlinked_unit.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:typed_data';
 
 import 'package:front_end/src/base/api_signature.dart';
 import 'package:front_end/src/fasta/parser/listener.dart' show Listener;
 import 'package:front_end/src/fasta/parser/parser.dart' show Parser, optional;
 import 'package:front_end/src/fasta/parser/top_level_parser.dart';
@@ skipping 101 matching lines @@
   @override
   Token parseFunctionBody(Token token, bool isExpression, bool allowAbstract) {
     if (identical('{', token.lexeme)) {
       Token close = skipBlock(token);
       bodyRanges.add(new _BodyRange(token.charOffset, close.charOffset));
       return close;
     }
     return super.parseFunctionBody(token, isExpression, allowAbstract);
   }
 
-  Token parseMixinApplication(Token token) {
+  Token parseMixinApplicationRest(Token token) {
     hasMixin = true;
-    return super.parseMixinApplication(token);
+    return super.parseMixinApplicationRest(token);
   }
 }