Add UBO offset support for D3D11.1. Also fixes the uniform count upper limit in glGetActiveUniformsiv. BUG=angleproject:507 Change-Id: Icfc90ed64cf94b1bab2d4cc93a8fb5e11b28d666 Reviewed-on: https://chromium-review.googlesource.com/261874 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>