Reviewed by Darin Adler.

        WebKit inserts base, link, meta, style, and title elements into an editable region
        when pasting table cells from Excel
        https://bugs.webkit.org/show_bug.cgi?id=60644

        Added a test to ensure WebKit strips the said elements prior to inserting HTML.

        * editing/pasteboard/paste-head-contents-expected.txt: Added.
        * editing/pasteboard/paste-head-contents.html: Added.
2011-05-12  Ryosuke Niwa  <rniwa@webkit.org>

        Reviewed by Darin Adler.

        WebKit inserts base, link, meta, style, and title elements into an editable region
        when pasting table cells from Excel
        https://bugs.webkit.org/show_bug.cgi?id=60644

        Strip base, link, meta, style, and tile elements from the fragment to be pasted prior
        to the merge. We don't have to strip these elements in performTrivialReplace because
        the function only handles a fragment that consists of exactly one text node.

        Test: editing/pasteboard/paste-head-contents.html

        * editing/ReplaceSelectionCommand.cpp:
        (WebCore::removeHeadContents): Added.
        (WebCore::ReplaceSelectionCommand::doApply): Calls removeHeadContents before handing
        style spans.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@86360 268f45cc-cd09-0410-ab3c-d52691b4dbfc