Drag and drop text and links doesn't work on Windows

As reported by fox in MDLQA-14467:

Using Windows 10, Firefox 76.0.1 and Chrome 76.0.3809.100 (Build officiel) (32 bits)

Steps to reproduce:

1. Log in as admin and go to Experimental settings and enable Drag and drop upload of text/links.
2. Log in as a teacher, go to a course and turn editing on.
3. Try selecting some text and dragging it to the course page.
4. Try selecting a link and dragging it to the course page.

Expected results:

• For text, you are asked if you wish to add a label or create a page resource.
• For a link, a URL resource is created with the link correctly filled in.

Actual results:

• When dragging text from a PDF or from Firefox into Chrome, it proposes to create a link.
• When dragging a link, the URL resource is created but the link is not filled in, only http://