User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:82.0) Gecko/20100101 Firefox/82.0

Steps to reproduce:

It's nice to see that firefox already supported custom search engines. (https://bugzilla.mozilla.org/show_bug.cgi?id=1106626 )

But, if firefox could set Icon for every engine, it will be better.

Just like this extension ( https://addons.mozilla.org/en-US/firefox/addon/add-custom-search-engine/ )

Actual results:

Default icon for all search engines

Expected results:

we can set the icon for earch engine

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

I think we should just use an appropriate favicon that Firefox knows of for the site. I don't think we need the capability to manually change/set it, since generally that would be complicated for most users and unnecessary in a lot of cases.

From a technical perspective, we should be able to use nsIFavIconService.getFaviconURLForPage, we probably also want to check that if it is the default favicon then we fallback to the search engine default favicon.