Vulkan: Assert that attributes in shader info map are active Attributes that are not active shouldn't have made it to the ShaderInterfaceVariableInfoMap of gl::ShaderType::Vertex. This change turns a few ifs to ASSERT in SpirvVertexAttributeAliasingTransformer. Bug: angleproject:4249 Change-Id: I3da4ea773eae20fe2f126b82f7790e9f2cab0bc1 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2491929 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>