Can icons define their own <style>?

Following the report of a custom icon uploaded in Designer causing the load of the UI to fail (no logs), we discovered that an icon that defines a <style> block with CSS rules inside could indeed be problematic.

What we need to understand:

• Why is that the case?
• Is this a problem for all Web UI versions?
• Can something be done in Web UI to avoid it?

On the Designer side, we could remove all <style> blocks when the icon is uploaded, but we would like to avoid that (if possible), as it would change how the icon looks.

Steps to reproduce:

• Install the attached zip package (NXP-28767.zip) on a 10.10 Nuxeo instance.
• When accessing Web UI, notice how the UI fails to load (NXP-28767-KO.png).
• Access .../nxserver/nuxeo.war/ui/nuxeo-mnixo-SANDBOX-iconset.html and comment or remove the style block (on the file_icon icon definition).
• Accessing Web UI again, the UI loads normally (NXP-28767-OK.png).