Split Renderbuffer::setStorage into two functions to match the API. BUG=angleproject:886 Change-Id: I74375351339464b450c2f058adbeed7a1ba18cdd Reviewed-on: https://chromium-review.googlesource.com/262125 Reviewed-by: Brandon Jones <bajones@chromium.org> Reviewed-by: Kenneth Russell <kbr@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>