I use VS2013.
I'm finding Microsoft.TeamFoundation.Git.Client.dll and The GitHttpClient resides in Microsoft.TeamFoundation.SourceControl.WebApi.dll . I can not find them from GAC.
I think that they may be in TFS SDK. But I can only find "Microsoft Visual Studio Team Foundation Server 2012 Software Development Kit for Java" :http://www.microsoft.com/en-us/download/details.aspx?id=22616.
Where can I get TFS SDK?
We now have NuGet packages for the .NET client libraries: .NET client libraries for Visual Studio Online (and TFS)
For the current Java SDK, it's part of the download for Team Explorer Everywhere 2015.
If you install Visual Studio 2013 Team Explorer, you will get the desired files.
http://www.microsoft.com/en-gb/download/details.aspx?id=40776
Regarding Microsoft.TeamFoundation.Git.Client.dll per MSDN :
I found that assembly in the PrivateAssemblies directory.
Regarding Microsoft.TeamFoundation.SourceControl.WebApi.dll per same page on MSDN:
That assembly is located in the bin folder of the Team Foundation Server. I also found that assembly in my GAC (although I'm not sure when it was installed).