the pre-allocation was needed because the layer allocated a opengl
context async itself and we couldn't influence that. so we had to start
the core after the context was actually allocated. furthermore a window,
view and layer hierarchy had to be created so the layer would create
a context.
now, instead of relying on the layer to create a context we do this
manually and re-use that context later when the layer wants to create
one async itself.
