Wrong rendered images when using <img> in less

[jcubic]

Issue summary

When you use XML <img> tag with less, it doesn't split the image into slices and it shows the scrollbar.

Expected behavior

It should work the same as with terminal formatting.

Steps to reproduce

See demo https://codepen.io/jcubic/pen/poMoyMg

Browser and OS

N/A

Additional notes

The problem is an empty object for attributes that is the output of the XML formatter

[jcubic]

There were two issues:

1. Wrong regex that test the image terminal formatting
2. There is a need to use option { formatting: true }

The second need to be documented