Allow ETC1_RGB8 for 2D array textures When GL_EXT_compressed_ETC1_RGB8_sub_texture is enabled, ETC1_RGB8 format must be accepted for 2D array textures. Bug: angleproject:5731 Change-Id: Ic5e647ffd4e7d2a171e25ea8cf3f41514cf37072 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4915918 Commit-Queue: Alexey Knyazev <lexa.knyazev@gmail.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>