Emit code to reset all buffer bindings to how they were at the
beginning during MEC.

Test: Capture Clash of Clans
Bug: angleproject:4048
Bug: b/172626835
Change-Id: I5a5446304d119f51a018c8fe88ff386243d19749
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2521179Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Commit-Queue: Cody Northrop <cnorthrop@google.com>