Environment API SetEnvironmentVariable change in Unity 5.3.5f1

I recently upgraded to Unity 5.3.5f1 and I notice the a line of code that previously compiled no longer does:

System.Environment.SetEnvironmentVariable(“MONO_REFLECTION_SERIALIZER”, “yes”)

My autocomplete seems to agree that this function no longer exists. Was there a change to the Mono version in 5.3.5f1 that could have removed this function?

The call was to enable serialization of objects to binary but perhaps it is un-necessary?

I am using MonoDevelop version 5.9.6 with Unity version 5.6.2f1, this statement “Environment.SetEnvironmentVariable(“MONO_REFLECTION_SERIALIZER”, “yes”);” just worked fine for me, I had to use it for class “BinaryFormatter” to avoid an exception.