Reviewed by John and TimH.
        
        <rdar://problem/4743256> Seed: Ctrl-Y key binding does nothing when kill ring is empty

        * editing/pasteboard/emacs-cntl-y-001-expected.checksum: Added.
        * editing/pasteboard/emacs-cntl-y-001-expected.png: Added.
        * editing/pasteboard/emacs-cntl-y-001-expected.txt: Added.
        * editing/pasteboard/emacs-cntl-y-001.html: Added.

WebKit:

        Reviewed by John and TimH.

        <rdar://problem/4743256> Seed: Ctrl-Y key binding does nothing when kill ring is empty

        Use deleteBackward: when the killring string is empty. Was always using insertText:,
        but that ends up early-returning if the string to insert is empty.
        
        * WebView/WebHTMLView.m:
        (-[NSArray yank:]):
        (-[NSArray yankAndSelect:]):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@16586 268f45cc-cd09-0410-ab3c-d52691b4dbfc