[jsonpath] Dot notation before bracket notation is not valid

Related issue:
uBlockOrigin/uBlock-issues#4052

Author: gorhill

src/js/jsonpath.js

@@ -254,6 +254,7 @@ export class JSONPath {
                 continue;
             }
             // Bracket accessor syntax
+            if ( mv === this.#CHILDREN ) { return; }
             if ( query.startsWith('[?', i) ) {
                 const not = query.charCodeAt(i+2) === 0x21 /* ! */ ? 1 : 0;
                 const j = i + 2 + not;