LibWeb: Allow whitespace in not after a boolean-expr-group

Author: https://github.com/lpas
Commit: 14dba82202
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6618
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/CSS/Parser/Parser.cpp

@@ -220,6 +220,7 @@ OwnPtr<BooleanExpression> Parser::parse_boolean_expression(TokenStream<Component
         tokens.discard_whitespace();
 
         if (auto child = parse_boolean_expression_group(tokens, result_for_general_enclosed, parse_test)) {
+            tokens.discard_whitespace();
             transaction.commit();
             return BooleanNotExpression::create(child.release_nonnull());
         }