Capture/Replay Tests: Fix Renderbuffer readback. Renderbuffer readback would use an unimplemented size function, ending up with a zero sized buffer. Also cleans up some of the code for reading back both Renderbuffers and Textures. One Depth/Stencil test that was crashing due to a recent change to read back depth data is now failing comparison because of missing combined depth/stencil support. Also updates the capture/reply self-test to handle ASAN-only test expectations. Bug: angleproject:4688 Change-Id: Idb6c05d15329f405f44502c2e5282764c7f780fb Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3119057 Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>