fix(core): escape brackets when transforming classes to selector (#8014)

Author: andreww2012

src/shared/classes-to-selector.mjs

@@ -1,6 +1,6 @@
 export default function classesToSelector(classes = '') {
   return `.${classes
     .trim()
-    .replace(/([\.:!+\/])/g, '\\$1') // eslint-disable-line
+    .replace(/([\.:!+\/()[\]])/g, '\\$1') // eslint-disable-line
     .replace(/ /g, '.')}`;
 }