--- Source/WebCore/css/makegrammar.pl.orig	2021-04-28 22:41:03.000000000 +0300
+++ Source/WebCore/css/makegrammar.pl	2021-04-28 22:42:11.000000000 +0300
@@ -91,5 +91,5 @@
 close HEADER;
 
 unlink("$fileBase.cpp.h");
-unlink("$fileBase.hpp");
+# not working for bison-3.7.x: unlink("$fileBase.hpp");