Fix stencil format exposure * Removed invalid STENCIL format table entry * Removed incorrect OpenGL ES 2.0 validation * Removed obsolete end2end test suppressions * Hid GL_OES_texture_stencil8 from ES 2.0 contexts * Marked unsized STENCIL_INDEX as never texturable * Marked unsized STENCIL_INDEX as never renderable Bug: angleproject:3231 Fixed: angleproject:5136 Change-Id: I3f2cb8240344db410773b6a5bde460a43eb32a2e Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4307120 Reviewed-by: Kenneth Russell <kbr@chromium.org> Commit-Queue: Alexey Knyazev <lexa.knyazev@gmail.com> Reviewed-by: Geoff Lang <geofflang@chromium.org>