Handle feed: URI scheme links in livemarks

[wesinator]

Is your feature request related to a problem? Please describe.

• https://www.malwaredomains.com/ , click the RSS icon Link is a feed: URI - feed:https://www.malwaredomains.com/?feed=rss2 opens Firefox application handler instead of livemarks

Describe the solution you'd like Open feed: URIs in livemarks

Describe alternatives you've considered

Additional context

[nt1m]

I looked at the navigator.register*Handler standards and unfortunately they don't work:

• https://developer.mozilla.org/en-US/docs/Web/API/Navigator/registerContentHandler (removed in Firefox 62)
• https://developer.mozilla.org/en-US/docs/Web/API/Navigator/registerProtocolHandler (doesn't allow registering the feed: protocol)

It might be possible to intercept someone visiting a feed: URI though using one of the webRequest/tabs/history API though.

[evilpie]

Now that Firefox doesn't handle feed: anymore, maybe we can make a compelling case to allow registerProtocolHandler for that scheme/protocol.

https://bugzilla.mozilla.org/show_bug.cgi?id=1571396