shiny/driver/gldriver: revert "update the open gl context after making it current"
shiny/driver/gldriver: revert "update the open gl context after making it current"

This reverts CL 154461.

[NSOpenGLContext update] must be called from the main thread if the
context has a view. The makeCurrentContext function is not called from
the main thread, so it is not thread safe to make a direct [ctx update];
call in it. Doing so causes gldriver to crash with a SIGILL signal when
compiled with Xcode 11.1 or newer on macOS Catalina.

Fixes golang/go#35177

Change-Id: I566c9526cddf31ed981312466f8843c2030d6692
Reviewed-on: https://go-review.googlesource.com/c/exp/+/212245
Reviewed-by: Nigel Tao <58ae08b3356928ff9c67562b4719487d54fe8348@golang.org>

golang/exp,golang/exp,golang/exp