my thought was that we wouldn't want to overwrite any classes already present on the element. (that might originate from the child view if that's what you're replacing, which is often my use case) — maybe there's a more efficient way to do this with the class string tho?

i can add a comment for `specified`. in IE8- instead of `el.attributes` giving you just the attrs that are specified, it gives you all of the attributes that _could_ be specified....... so the `specified` property was introduced. 

and then there's also a `length` property of the `NamedNodeMap` that we'll run into as well which we don't want either, and it won't have a `specified` attr either. 

open to a different way to handle this tho if you have ideas