Fix up various issues leading to bug 40780.
* jquery.autoEllipsis didn't return 'this', which means whenever it
was used in a chain, it would return undefined.
So in mediawiki.searchSuggest append( ... autoEllipsis() ) would
apply it to a detached node that stays detached because it
isn't passed to append.
* Remove redundant passing of this in jQuery context to $().
On jQuery.prototype, 'this' is obviously a jQuery object. In
jquery.highlightText, which is called from jquery.autoEllipsis.
* Remove redundant .empty() call before calling .text( .. ),
.text() replaces all content and naturally is forced to empty
the element first.
* Merge use of $el and $container in jquery.autoEllipsis.js. They
were both pointing to the same object, having two names was only
confusing.
* Spaces.
Change-Id: I4649ec0c89d38c4d79d1dceec28227902cd48d32