Revert "Implement EXT_discard_framebuffer in D3D11 renderer" Causes failures in video related WebGL tests. Either there is a bug in the implementation or how chrome is using it. This reverts commit b13daa8f79f4d16a990d968d7d2c04da6b72d302. Change-Id: Ic0d74840c664bf4de18d85cc3ff7f7153936d9b0 Reviewed-on: https://chromium-review.googlesource.com/262715 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>