title: Referencing a .NET 4.6 project from ASP.NET 5 causes build error
body: <p>In my ASP.NET 5 RC1 project (targeting only dnx46) I'm trying to add a reference to a (classic) Class Library project targeting .net 4.6. </p>
  
  <p>I get this error at build time:
  ...\MSBuild\14.0\bin\Microsoft.Common.CurrentVersion.targets(1819,5): warning MSB3274: The primary reference "...\ClassLibrary1.dll" could not be resolved because it was built against the ".NETFramework,Version=v4.6" framework. This is a higher version than the currently targeted framework ".NETFramework,Version=v4.5.1".</p>
  
  <p>Why is this happening? My ASP.NET 5 project isn't targeting 4.5.1. According to the project.json file it's only targeting dnx46. I can't find any mention of .net 4.5.1 anywhere.</p>
  
  <p>Here's the project.json for my WebApplication project:</p>
  
  <pre><code>{
    "version": "1.0.0-*",
    "compilationOptions": {
      "emitEntryPoint": true
    },
  
    "dependencies": {
      "Microsoft.AspNet.IISPlatformHandler": "1.0.0-rc1-final",
      "Microsoft.AspNet.Server.Kestrel": "1.0.0-rc1-final"
    },
  
    "commands": {
      "web": "Microsoft.AspNet.Server.Kestrel"
    },
  
    "frameworks": {
      "dnx46": {
        "dependencies": {
          "ClassLibrary1": "1.0.0-*"
        }
      },
    },
  
    "exclude": [
      "wwwroot",
      "node_modules"
    ],
    "publishExclude": [
      "**.user",
      "**.vspscc"
    ]
  }
  </code></pre>
  
  <p>And here's the project.json that the "wrapping" process creates for my ClassLibrary project:</p>
  
  <pre><code>{
    "version": "1.0.0-*",
    "frameworks": {
      "net46": {
        "wrappedProject": "../../ClassLibrary1/ClassLibrary1.csproj",
        "bin": {
          "assembly": "../../ClassLibrary1/obj/{configuration}/ClassLibrary1.dll",
          "pdb": "../../ClassLibrary1/obj/{configuration}/ClassLibrary1.pdb"
        }
      }
    }
  }
  </code></pre>