LibWeb/HTML: Port Window.isSecureContext to IDL

Author: https://github.com/linusg
Commit: 94f1eff291
Pull-request: https://github.com/SerenityOS/serenity/pull/17752
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/HTML/Window.h

@@ -257,7 +257,6 @@ private:
 
     JS_DECLARE_NATIVE_FUNCTION(local_storage_getter);
     JS_DECLARE_NATIVE_FUNCTION(session_storage_getter);
-    JS_DECLARE_NATIVE_FUNCTION(is_secure_context_getter);
 
     JS_DECLARE_NATIVE_FUNCTION(set_interval);
     JS_DECLARE_NATIVE_FUNCTION(set_timeout);