Reviewed by Darin Adler.

        Opacity transition doesn't work while content property is set.
        https://bugs.webkit.org/show_bug.cgi?id=59301

        StyleRareNonInheritedData's copy constructor omitted to copy
        the m_content data, which caused us to detach and re-attach the renderer
        at the start of the transition, thereby killing the transition.

        Fix by making StyleRareNonInheritedData's copy ctor do the right thing.

        Test: transitions/transition-on-element-with-content.html

        * rendering/style/ContentData.h:
        * rendering/style/ContentData.cpp:
        (WebCore::ContentData::clone): New method to do a deep clone. (Can't use a copy
        ctor because of the subclasses.)
        * rendering/style/CounterDirectives.h: Pack the data members to save space.
        Add a clone() function for the HashMap.
        * rendering/style/CounterDirectives.cpp:
        (WebCore::clone): Make a new HashMap and copy the contents over.
        * rendering/style/StyleRareNonInheritedData.cpp:
        (WebCore::StyleRareNonInheritedData::StyleRareNonInheritedData): Copy
        the content and counter directives over.
        (WebCore::StyleRareNonInheritedData::operator==): Rather than just comparing
        for pointer equality, do a correct check for m_counterDirectives equality.
        (WebCore::StyleRareNonInheritedData::counterDataEquivalent):
        * rendering/style/StyleRareNonInheritedData.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@88308 268f45cc-cd09-0410-ab3c-d52691b4dbfc