We used to check if the passed query looked like a tag name so we could
bail out early, as we'd get those results from _searchIndex.
But InspectorUtils.isCustomElementName does match some legitimate
selectors, like div.a-b.
Let's remove the check on custom element and trigger the search in such case.
Original Revision: https://phabricator.services.mozilla.com/D259783
Differential Revision: https://phabricator.services.mozilla.com/D260238
8a33ca95a6