Vulkan: SPIR-V Gen: Enable GLSLTest* This change includes an assortment of small fixes to enable most of GLSLTest* end2end tests. - User-defined std140 storage buffers were mistakenly turned to std430. - External and WEBGL samplers were redundantly redeclaring the sampler2D type. - `invariant` specified on a field of struct type didn't apply it to said struct's members. - Arrays of struct as a member of an interface block didn't have their size aligned, producing incorrect stride - Interpolation and auxiliary qualifiers are now generated - Arrays of opaque uniforms are now correctly passed to functions when indexed. - atan(x, y)'s built-in Op is fixed - early_fragment_tests is now generated Additionally, the SPIR-V transformer didn't handle the Invariant decoration applied to gl_PerVertex built-ins, which is possible as a result of: #pragma STDGL invariant(all) This bug existed in the transformer due to two bugs: - ANGLE didn't generate this line when generating GLSL to feed to glslang. This is fixed by this change. - glslang itself ignores this line: https://github.com/KhronosGroup/glslang/issues/2689 Bug: angleproject:4889 Change-Id: I15ad9fcc178abc1eae944e7a58f4e6153fa5dfd9 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3016762 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>