Restore missing [ComVisible]

It turns out that this was needed (in spite of a Code Analysis warning
about the lack of public constructor) to expose to WebBrowser via
ObjectForScripting.

Fixes 34b5f77d71d3b5420986ca74f18ead1a94a2607b
Selector Quick Info: Don't show mixin specificity
Unify namespaces

Change namespace from copied sample code
Add more CSS / LESS identifier highlighting

Variable names, mixin names, property names