Issue when removing a base64 encoded image from comment

[Lisa Seeto]

Mahara 18.10 master
OS: Linux
Postgres
Firefox 65.0.1

You can add a base64 encoded image to a text field such as a comment. This functionality was introduced when addressing this issue: https://bugs.launchpad.net/mahara/+bug/1742590
The maxLength attr for the field was altered to accept up to 1 million characters allowing a base64 image to be able to be added to a comment. After the comment is saved, editing the comment by viewing the source code reveals that the image has been converted into a blob, i.e: <img src="blob:http://mahara/ce5b1d93-d955-49bb-8f6b-1a6e12a7d509" alt="Z" />. When you delete the comment a warning is produced:

[WAR] fa (lib/htmltotext/htmltotext.php:27) DOMDocument::loadHTML(): Misplaced DOCTYPE declaration in Entity, line: 1 (please see attached screen shot)