gn: delete some dead code

tools/gn/operators.h

Index: tools/gn/operators.h
diff --git a/tools/gn/operators.h b/tools/gn/operators.h
index 3401c225ba0f7d073bf0e3b11255e76ab1d11385..82ff68e7578d3245cf195c312110ddf50773bacb 100644
--- a/tools/gn/operators.h
+++ b/tools/gn/operators.h
@@ -9,19 +9,9 @@ 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,