[Search] trigger 'focusin', 'focusout'.

[dreaming-augustin]

Trigger 'focusin' and 'focusout' whenever a search result item becomes active.

It allows websites to implement a solution for this:

[Search] Bring active result into view #3143

[dreaming-augustin]

This patch at least allows for a partial solution to [Search] Bring active result into view #3143

It allows websites to implement their own solution, according to their needs.
A website in now able to implement something like the following on their own:

        // Scroll  search results into view.
        $('#search').on('focusin', '.result', function() {
                var offset = $(this).offset();
                var viewportTop    = $(window).scrollTop();
                var viewportHeight = $(window).height();
                var viewportBottom = viewportTop + viewportHeight;
                var elementTop     = $(this).offset().top;
                if (elementTop > (viewportBottom - 150)) {
                        offset.top = elementTop - (viewportHeight / 4);
                        $('html, body').animate({
                                scrollTop: offset.top,
                        }, 200);
                }
                if (elementTop < (viewportTop + 150)) {
                        offset.top = elementTop - (3 * viewportHeight / 4);
                        $('html, body').animate({
                                scrollTop: offset.top,
                        }, 200);
                }
        });

This feels a bit hackish and too specific. It can be discussed whether something more appropriate could be considered to be included within Fomantic.

At the very least, triggering focusin(), developers have more options to deal with their own business needs.