Use metadata annotation @patch for patch classes

runtime/vm/parser.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_PARSER_H_
 #define VM_PARSER_H_
 
 #include "include/dart_api.h"
 
 #include "platform/assert.h"
@@ skipping 383 matching lines @@
   String* ExpectUserDefinedTypeIdentifier(const char* msg);
   String* ExpectIdentifier(const char* msg);
   bool IsAwaitKeyword();
   bool IsYieldKeyword();
 
   void SkipIf(Token::Kind);
   void SkipToMatching();
   void SkipToMatchingParenthesis();
   void SkipBlock();
   TokenPosition SkipMetadata();
+  bool IsPatchAnnotation(TokenPosition pos);
   void SkipTypeArguments();
   void SkipType(bool allow_void);
   void SkipInitializers();
   void SkipExpr();
   void SkipNestedExpr();
   void SkipConditionalExpr();
   void SkipBinaryExpr();
   void SkipUnaryExpr();
   void SkipPostfixExpr();
   void SkipSelectors();
@@ skipping 552 matching lines @@
 
   intptr_t recursion_counter_;
   friend class RecursionChecker;
 
   DISALLOW_COPY_AND_ASSIGN(Parser);
 };
 
 }  // namespace dart
 
 #endif  // VM_PARSER_H_