GL: Move draw functions from Renderer to Context. This avoids one more function call + register pushing/popping. Slight improvement in the command_buffer_perftests. Bug: angleproject:2877 Change-Id: Ia50a330e62f0bd32266c9f0999810243cbaa41e0 Reviewed-on: https://chromium-review.googlesource.com/c/1293630 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>