Cleanup remaining class/struct fwd declarations

tools/gn/functions.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TOOLS_GN_FUNCTIONS_H_
 #define TOOLS_GN_FUNCTIONS_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/strings/string_piece.h"
 
 class Err;
 class BlockNode;
 class FunctionCallNode;
 class Label;
 class ListNode;
 class ParseNode;
 class Scope;
-class Token;
 class Value;
 
 // -----------------------------------------------------------------------------
 
 namespace functions {
 
 // This type of function invocation has no block and evaluates its arguments
 // itself rather than taking a pre-executed list. This allows us to implement
 // certain built-in functions.
 typedef Value (*SelfEvaluatingArgsFunction)(Scope* scope,
@@ skipping 464 matching lines @@
   Scope* scope_;
   const FunctionCallNode* function_;
   const char* type_description_;
 
   // Set to true when the key is added to the scope so we don't try to
   // delete nonexistant keys which will cause assertions.
   bool key_added_;
 };
 
 #endif  // TOOLS_GN_FUNCTIONS_H_