Use both null and real renders for draw call perf. Introduce a "null" GL renderer for this specific benchmark, which does not do any work on drawArrays and drawElements. We could use the same kind of trick for buffer and texture updates, if we need it. This gives us a good baseline for comparing GL and D3D perf. BUG=angleproject:1040 Change-Id: I4bf7c75df01932de45ddd0a4e42e8fc82f15e37e Reviewed-on: https://chromium-review.googlesource.com/276192 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Kenneth Russell <kbr@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>