Add a perf test for render-to-texture. This perf test focuses on the hotspot we have in Framebuffer:: checkStatus. It's exactly the same as the standard draw call benchmark, but binds a Framebuffer before rendering. BUG=angleproject:1388 Change-Id: Icc7a99e399f469d765bf1ac6abe0562977b9a39d Reviewed-on: https://chromium-review.googlesource.com/348956 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>