Initialize gl::Context state on the first call to MakeCurrent. The constructor of gl::Context creates a bunch of zero and helper objects but it is not current at this time. If the backend if not using virtualized contexts this causes the created objects to be created on the wrong native context. BUG=angleproject:2464 Change-Id: I9718df87d0afeb08729920363d362d5f891061ed Reviewed-on: https://chromium-review.googlesource.com/1048114 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Luc Ferron <lucferron@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>