Reviewed by Sam Weinig.

        Skip (and in a few cases fix) tests for WebKit2
        https://bugs.webkit.org/show_bug.cgi?id=52698

        * editing/pasteboard/copy-null-characters.html: Make this test fail in a more
        obvious way when it fails.
        * fast/events/scroll-event-does-not-bubble.html: Make this test properly
        handle the fact that scroll events are async. The job was half-done before.
        * platform/mac-wk2/Skipped: Skip!


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@76097 268f45cc-cd09-0410-ab3c-d52691b4dbfc