We will need the Renderer pointer for resource allocation, so
pass it around instead of storing the device and context.

BUG=angleproject:2034

Change-Id: Iaf271913f88c5402895aa81de310aa22fcd72cc4
Reviewed-on: https://chromium-review.googlesource.com/509930Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>