The KHR GLES31 tests disabled and marked with Issue 4146 are passing,
likely due to the work for Issue 3570: Vulkan: Implement separate
shader objects or program pipeline objects. This CL re-enables the
tests.

Bug: angleproject:4146
Bug: angleproject:3570
Test: KHR-GLES31.core.shader_storage_buffer_object.basic-syntaxSSO
Test: KHR-GLES31.core.vertex_attrib_binding.advanced-bindingUpdate
Test: KHR-GLES31.core.vertex_attrib_binding.advanced-largeStrideAndOffsetsNewAndLegacyAPI
Change-Id: I4e42129c873604c937cf03412a105170755413e3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2318265Reviewed-by: Charlie Lao <cclao@google.com>
Commit-Queue: Tim Van Patten <timvp@google.com>