Fix validating argument for :not() as procedural

Related feedback:
- https://github.com/uBlockOrigin/uBlock-issues/issues/2228#issuecomment-1234248802

src/js/static-filtering-parser.js

@@ -1615,6 +1615,7 @@ Parser.prototype.SelectorCompiler = class {
         if ( this.querySelectable(s) === false ) {
             return this.compileProcedural(s);
         }
+        return s;
     }
 
     compileUpwardArgument(s) {