Add a B8G8R8X8 type for mipmaping, reading and writing D3D9 BGR textures. Fixes WebGL D3D9 conformance failures in: context-attributes-alpha-depth-stencil-antialias copy-tex-image-2d-formats.html texture-attachment-formats.html BUG=angle:550 Change-Id: I09d42c5e6cf7d880841207627fd20698ed188a6a Reviewed-on: https://chromium-review.googlesource.com/191935 Tested-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Shannon Woods <shannonwoods@chromium.org>