Reproduction steps:
1. Open any project
2. Try to build & run
3. Fails with the following output:

Exception: Failed to build Visual Studio project using arguments 'C:\Program Files (x86)\MSBuild\14.0\Bin\MSBuild.exe "F:\Work\Metro\_BUILD\New Unity Project.sln" /nologo /maxcpucount /p:Configuration=Master /p:Platform=x86 /p:SolutionDir="F:\\Work\\Metro\\_BUILD\\" /t:Build /clp:Verbosity=minimal'.
Output:F:\Work\Metro\_BUILD\New Unity Project\New Unity Project.csproj : XamlCompiler error WMC1006: Cannot resolve Assembly or Windows Metadata file 'Windows.Foundation.UniversalApiContract.winmd'
C:\Program Files (x86)\MSBuild\Microsoft\WindowsXaml\v14.0\8.2\Microsoft.Windows.UI.Xaml.Common.targets(264,5): Xaml Internal Error error WMC9999: Type universe cannot resolve assembly: Windows.Foundation.UniversalApiContract, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null, ContentType=WindowsRuntime. [F:\Work\Metro\_BUILD\New Unity Project\New Unity Project.csproj]

Reproducible only with 5.5.x versions