Populate the entrypoints required to get gfxBench
Manhattan scene to capture and replay correctly from
the beginning of the trace.

Test: Captured and replayed Manhattan frames 0-500 on
both Windows and Linux (Nvidia GPUs)

Bug: angleproject:4091
Change-Id: I5447a6835e55e944772d37219f2bd414606f0a70
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2029216Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Commit-Queue: Cody Northrop <cnorthrop@google.com>