Reviewed by Kevin.

    Reviewed by Kevin.

        - some garbage collection fixes

        * Misc.subproj/WebNSObjectExtras.h: (WebCFAutorelease): Replaced the old WebNSRetainCFRelease with this
        much-easier-to-understand function cribbed from what David Harrison did in WebCore.

        * Misc.subproj/WebKitNSStringExtras.m: (+[NSString _web_encodingForResource:]): Use CFRelease here to
        get rid of an unnecessary use of WebNSRetainCFRelease.
        * Misc.subproj/WebNSURLExtras.m:
        (+[NSURL _web_URLWithData:relativeToURL:]): Use WebCFAutorelease instead of WebNSRetainCFRelease and autorelease.
        (-[NSURL _web_URLWithLowercasedScheme]): Ditto.
        (-[NSString _web_mapHostNameWithRange:encode:makeString:]): Use WebCFAutorelease here; the old code would not
        work correctly under GC.
        * Plugins.subproj/WebNetscapePluginPackage.m: (+[WebNetscapePluginPackage preferredLocalizationName]):
        Use WebCFAutorelease here; the old code would not work correctly under GC.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@8255 268f45cc-cd09-0410-ab3c-d52691b4dbfc