Stop traversing up the tree looking for ScopedStyleResolvers.

Stop traversing up the tree looking for ScopedStyleResolvers.

There's no reason to collect resolvers up the tree, only the element's
scope can ever contain matching rules except for tree boundary crossing
rules or :host/:host-context rules and we deal with those separately.

This also exposes that CascadeScope is dead code and we can remove it.

BUG=372083

[esprehn, 2014-09-18 23:09:52]

This patch depends on https://codereview.chromium.org/581663003

[esprehn, 2014-09-19 01:32:36]

esprehn@chromium.org changed reviewers:
+ dglazkov@chromium.org, kochi@chromium.org, ojan@chromium.org

[tasak, 2014-09-19 02:28:27]

On 2014/09/19 01:32:36, esprehn wrote:

I think, this patch should consider -webkit prefixed custom pseudo, e.g.

<style>
input::-webkit-slider-thumb { ... }
</style>

[esprehn, 2014-09-19 02:56:53]

On 2014/09/19 02:28:27, tasak wrote:
> On 2014/09/19 01:32:36, esprehn wrote:
> 
> I think, this patch should consider -webkit prefixed custom pseudo, e.g.
> 
> <style>
> input::-webkit-slider-thumb { ... }
> </style>

I see, we do need to traverse up the tree, but only for elements with
shadowPseudoId().