<rdar://problem/4841123>
        REGRESSION: Crash in WebCore::Range::boundaryPointsValid when replying to a mail Message
        
        * Misc/WebNSAttributedStringExtras.m:
        (+[NSAttributedString _web_attributedStringFromRange:]):
        If the range passed in is null, return null. When this function was in the bridge, it would never get called
        with a null range when nothing was selected. Instead, the range would just have invalid boundary points.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@17813 268f45cc-cd09-0410-ab3c-d52691b4dbfc