This will more easily allow us to call gl::BindingPointer methods.
The binding pointer will be used temporarily in the command graph.
This is only temporary since we will likely not be using
BindingPointer in the end result code, but it could be necessary
for future work.

Bug: angleproject:2264
Change-Id: I33cf40ec2a1e334c4abfdcff2ad20bbcda3c9d78
Reviewed-on: https://chromium-review.googlesource.com/789532Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>