sniffing

Today a user needs to uninstall BruteShark using the control panel before installing a new version.
Using the WiX installer enable to upgrade the installation if the version is higher than the current version.

https://www.iana.org/assignments/media-types/image/jxr
https://www.iana.org/assignments/media-types/image/jxs

In https://mimesniff.spec.whatwg.org/#parsing-a-mime-type the following step might be clearer if it explicitly said the trailing sequence after " was to be discarded. Might also be better if the example contains a ';' since the step mentions ';'

Current:

Collect a sequence of code points that are not U+003B (;) from input, given position.
Example: Given text/html;charset="shift_jis"iso-20