Fix #14492: More correct jQuery.parseJSON

```
   raw     gz Sizes                                                            
281021  83422 dist/jquery.js
 96006  33281 dist/jquery.min.js

   raw     gz Compared to 1.x-master @ 90d9c4632c1f05f32ead98b46796bed9635e40fb
  +226   +126 dist/jquery.js
   -15     +2 dist/jquery.min.js
```