fix portable build

Telerik.JustMock/DebugView.cs

@@ -183,7 +183,12 @@ namespace Telerik.JustMock
 		}
 #endif
 
-		internal static Action<string> DebugTrace = s => System.Diagnostics.Trace.WriteLine(s);
+		internal static Action<string> DebugTrace = s =>
+#if PORTABLE
+			System.Diagnostics.Debug.WriteLine(s);
+#else
+			System.Diagnostics.Trace.WriteLine(s);
+#endif
 	}
 }