First round of dead file removal

experimental/visual_studio_plugin/src/MsAd7.BaseImpl/SimpleExpression.cs

-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using Microsoft.VisualStudio;
-using Microsoft.VisualStudio.Debugger.Interop;
-
-namespace Google.MsAd7.BaseImpl
-{
-  class SimpleExpression : IDebugExpression2
-  {
-    public SimpleExpression(DebugPropertyBase property) {
-      property_ = property;
-    }
-
-    public DebugPropertyBase Property {
-      get { return property_; }
-    }
-
-    #region Implementation of IDebugExpression2
-
-    public int EvaluateAsync(enum_EVALFLAGS dwFlags, IDebugEventCallback2 pExprCallback) {
-      throw new NotImplementedException();
-    }
-
-    public int Abort() {
-      throw new NotImplementedException();
-    }
-
-    public int EvaluateSync(enum_EVALFLAGS dwFlags, uint dwTimeout, IDebugEventCallback2 pExprCallback, out IDebugProperty2 ppResult) {
-      ppResult = property_;
-      return VSConstants.S_OK;
-    }
-
-    #endregion
-
-    private DebugPropertyBase property_;
-  }
-}