CSS on dynamic DOM

[Maksim Orlovich]

> Hi all
>
> Here's a patch to implement correct CSS on dynamic DOM. I am not yet sure
> it
> handles all corner-cases, but it handles at lot and all the attached
> test-cases.

A couple comments w/o having access to source tree and net at once, e.g.
w/o being able to test it (and please keep in mind I've been working a bit
on making selector matching more efficient):

0. This is very nice to see, great work overall.
1. Why do you need attribute dependencies?
2. in ElementImpl::attributeChanged you -Force- a recalc for id/classname.
That's super-duper expensive. I guess the reason is that you skip the
attribute dependency stuff for id/classname, so this is really a disguised
#1.
3. Worse, in ElementImpl::attributeChanged you call restyleDependent which
forces a recalcStyle immediately. Any reason not to rely on proper lazy
restyling to get it right? Right now you may be recomputing stuff over and
over again while a node is being yanked around.

-Maks