It has become unnecessary after the switch from GLFW v3.2 to v3.3, because Window.GetCocoaWindow now returns unsafe.Unsafe directly.
9364696d8c28dc804dcd7e099f0b7c6cb58ac824
It has been released recently. Start using it. Updates https://github.com/go-gl/glfw/pull/256
fec1b7b612ab0b81aa1d8b5c9a58c795f94fd767
Get the ContentView right away, instead of going through cocoaWindow. The ContentView is all that's needed from cocoaWindow at this time. This is simpler and reads better.
c9d1ccdd732c27473f903791c278423da078587e