fix subtitle position after seek in chrome

MediaBrowser.Model/Dlna/TranscodingProfile.cs

@@ -29,6 +29,9 @@ namespace MediaBrowser.Model.Dlna
         [XmlAttribute("transcodeSeekInfo")]
         public TranscodeSeekInfo TranscodeSeekInfo { get; set; }
 
+        [XmlAttribute("copyTimestamps")]
+        public bool CopyTimestamps { get; set; }
+
         [XmlAttribute("context")]
         public EncodingContext Context { get; set; }