With the extension enabled, html tags (all of themexcept for script as far as I could find) all have the textmate scope meta.tag.other.unrecognized.html.derivative instead of (for a body tag for example) meta.tag.structure.body.start.html / meta.tag.structure.body.end.html.
I discovered this when I tried to edit a theme to mute the closing tags for a more slim / pug type editing experience.