These are changes that VS 2013 wants us to make to our test project files.
I figured we might as well do this and get it over with rather than let someone
struggle with this in the middle of another change.

It's intentionally inserting this block into our test projects when they
are opened. See
http://connect.microsoft.com/VisualStudio/feedback/details/800245/vs2013rc-adds-to-vs2012-c-project-section-itemgroup
for more details. Yes, the link says RC, but this is happening in RTM.