Move default ANGLE format map to shared location. This default format mapping serves as a base for a Renderer format mapping. Any formats that require emulation or other representation in a Renderer can be overridden in the renderer layer. BUG=angleproject:1455 Change-Id: I47f070c2ea132bada9cc0fc4353b89b74b8ee8f3 Reviewed-on: https://chromium-review.googlesource.com/367692 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>