StyledElement: Tweak signature of collectStyleForPresentationAttribute().
<http://webkit.org/b/110687>

Reviewed by Antti Koivisto.

Out with the old:
    collectStyleForPresentationAttribute(const Attribute&, StylePropertySet*)

In with the new:
    collectStyleForPresentationAttribute(const QualifiedName&, const AtomicString&, MutableStylePropertySet*)

This is primarily about switching to using MutableStylePropertySet* in preparation for
removing mutating functions from the StylePropertySet base class.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143843 268f45cc-cd09-0410-ab3c-d52691b4dbfc