JavaScript has added things, not removed them.
There are other HTML elements and attributes that were never in any spec and were supported by only some browsers, which are no longer supported (either it was IE, or the feature was removed), and explicitly described as obsolete in the HTML Standard. But they were never supported by more than two of the three or four main engines, or if they were their functionality has been retained.
So, if you have anything that has actually been removed from the web platform, please be more specific.