gn: delete some dead code

tools/gn/operators.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_OPERATORS_H_
 #define TOOLS_GN_OPERATORS_H_
 
 class BinaryOpNode;
 class Err;
 class ParseNode;
 class Scope;
-class Token;
 class UnaryOpNode;
 class Value;
 
-bool IsUnaryOperator(const Token& token);
-bool IsBinaryOperator(const Token& token);
-
-bool IsFunctionCallArgBeginScoper(const Token& token);  // "("
-bool IsFunctionCallArgEndScoper(const Token& token);  // ")"
-
-bool IsScopeBeginScoper(const Token& token);  // "{"
-bool IsScopeEndScoper(const Token& token);  // "}"
-
 Value ExecuteUnaryOperator(Scope* scope,
                            const UnaryOpNode* op_node,
                            const Value& value,
                            Err* err);
 Value ExecuteBinaryOperator(Scope* scope,
                             const BinaryOpNode* op_node,
                             const ParseNode* left,
                             const ParseNode* right,
                             Err* err);
 
 #endif  // TOOLS_GN_OPERATORS_H_