Remove incorrect WTF::Vector traits for CSSProperty.

Remove incorrect WTF::Vector traits for CSSProperty.
<http://webkit.org/b/53285>
<rdar://problem/10161286>

Reviewed by Antti Koivisto.

We shouldn't allow copying Vector<CSSProperty> contents around with memcpy()
as CSSProperty has a RefPtr member and this would muck up the refcount.
This was added to facilitate fast comparison of property vectors, and we no
longer use that, so there shouldn't be any performance concerns here.

* css/CSSProperty.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@109893 268f45cc-cd09-0410-ab3c-d52691b4dbfc