- speculative fix for <rdar://problem/5509989> CrashTracer: [USER] 1 crash in Safari at com.apple.WebKit: 
        -[WebPDFView(FileInternal) _updatePreferencesSoon] + 56
        
        The crash is probably due to messaging a dealloc'ed dataSource ivar. The dataSource ivar isn't retained
        by this class, but should be. (It is retained by WebHTMLView, e.g.).

        * WebView/WebPDFView.mm:
        (-[WebPDFView dealloc]):
        release dataSource ivar
        (-[WebPDFView setDataSource:]):
        retain dataSource ivar



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@27718 268f45cc-cd09-0410-ab3c-d52691b4dbfc