Reviewed by Darin Adler.

        HTMLTable should cache its 'rows' collection results
        https://bugs.webkit.org/show_bug.cgi?id=62800

        * perf/table-rows-length-caching-expected.txt: Added.
        * perf/table-rows-length-caching.html: Added.
        This test checks that the call to table.rows is CONSTANT once it has
        been populated once (and the DOM is not mutated).
2011-06-16  Julien Chaffraix  <jchaffraix@webkit.org>

        Reviewed by Darin Adler.

        HTMLTable should cache its 'rows' collection results
        https://bugs.webkit.org/show_bug.cgi?id=62800

        Test: perf/table-rows-length-caching.html

        Currently all our HTMLCollection's are recreated on call. This means that
        we don't cache the information about the collection between calls to, for
        example, table.rows.

        This change adds a CollectionCache to HTMLTableElement. It is similar to what
        is done for HTMLFormElement.

        * html/HTMLTableElement.cpp:
        (WebCore::HTMLTableElement::collectionCache): This method does
        lazy initialization of the table's collectionCache.
        * html/HTMLTableElement.h: Added a new member and the previous
        method.

        * html/HTMLTableRowsCollection.cpp:
        (WebCore::HTMLTableRowsCollection::HTMLTableRowsCollection): Pass
        the HTMLTableElement's CollectionCache so that we reuse the cached
        results.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@89035 268f45cc-cd09-0410-ab3c-d52691b4dbfc