When you float a image 'left' inside a quotebox, it goes outside the qoutbox. But when you view it from the post itself, it looks to be okay.
Screenshot from the editor view:
http://imgur.com/CZVOUe5
The example below will look okay from the person seeing it as the rendered post.
I'm using
Firefox 54.0.1
Quote[Blocked Image: http://via.placeholder.com/350x350]Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer vehicula enim magna, finibus placerat diam tincidunt vel. Maecenas a sem in est feugiat auctor sit amet rutrum ex. Cras id lacus scelerisque magna consectetur interdum. Nulla nunc nisi, lobortis in magna non,