Visual Studio 2010 changes the .csproj file's reference to Microsoft.VisualStudio.QualityTools.UnitTestFramework
aggressively upon each edit of test projects. In particular, it changes the following:

    <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework" Condition=" '$(BuildPlatform)' == 'DESKTOPCLR' " />

into

    <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework" />

dropping the conditional include. In order to reach a fixpoint when opening the project, we choose to include
a file with the name Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll in every reference assemblies
folder. This file actually contains the testing suite used and ***IS NOT NECESSARILY*** the same as the one
used for desktop CLR (which has that name).

In particular, for Silverlight, this file is a rename of

    Microsoft.VisualStudio.QualityTools.UnitTesting.Silverlight.dll

into

    Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll