I can confirm 100% that W8 theme has it, because when I downloaded the 1129 version 2-3 days ago ( I downloaded the dlls version only, not internal build, but official release), and imported the xaml files in the project, it did not compile. Then I searched the indicator in the dll itself, it was gone, so I removed it
It should be just a matter if a search thing, just search through zip files, and you will see that it exists. The zip file I have is:
dated 29.11.2012 20:37
answered on 10 Dec 2012, 12:00 PM
Indeed I've searched exactly these files from our official Q3 2012 SP1. There is no such class in Telerik.Windows.Controls.GanttView.xaml.