Stop directly referencing the `Protocol` class symbol
Stop directly referencing the `Protocol` class symbol

- This class appears to have been moved private on some platforms with
  Xcode 7.3. Dynamically looking up the class at runtime still works though.
lumoslabs/blindside,lumoslabs/blindside,lumoslabs/blindside,jbsf/blindside,jbsf/blindside,jbsf/blindside