The only piece of data left in the d3d11::TextureFormat is the
initializer function, which could just as easily be in the
ANGLEFormatSet.

BUG=angleproject:1455

Change-Id: Iee8eb84f71807575c2a46bf4fcbf283aa1b7f565
Reviewed-on: https://chromium-review.googlesource.com/367090Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>