Implement TexStorage2DMultisample and getMultisamplefv entry point. Also modify sample state for Textures and Framebuffers. BUG=angleproject:1590 TEST=angle_unittests TEST=angle_end2end_tests TEST=dEQP-GLES31.functional.texture.multisample.samples_*.sample_position TEST=dEQP-GLES31.functional.texture.multisample.samples_*.use_texture_color_2d TEST=dEQP-GLES31.functional.texture.multisample.samples_*.use_texture_depth_2d TEST=dEQP-GLES31.functional.texture.multisample.negative.fbo_attach_different_sample_count_tex_tex TEST=dEQP-GLES31.functional.texture.multisample.negative.fbo_attach_different_sample_count_tex_rbo TEST=dEQP-GLES31.functional.texture.multisample.negative.fbo_attach_non_zero_level TEST=dEQP-GLES31.functional.texture.multisample.negative.texture_high_sample_count TEST=dEQP-GLES31.functional.texture.multisample.negative.texture_zero_sample_count TEST=dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_1_texture_2d TEST=dEQP-GLES31.functional.shaders.builtin_functions.texture_size.samples_4_texture_2d Change-Id: I8fa7bd4e73b95745858a3e16b1b92004b4a18712 Reviewed-on: https://chromium-review.googlesource.com/414309 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Yunchao He <yunchao.he@intel.com> Reviewed-by: Geoff Lang <geofflang@chromium.org>
