Shaders: wait, this should work, and not assert.

src/Magnum/Shaders/Test/PhongGLTest.cpp

@@ -231,6 +231,8 @@ constexpr struct {
     {"vertex colors + diffuse texture", PhongGL::Flag::VertexColor|PhongGL::Flag::DiffuseTexture, 1},
     #ifndef MAGNUM_TARGET_GLES2
     {"object ID", PhongGL::Flag::ObjectId, 1},
+    /* This is fine, InstancedObjectId isn't (check in ConstructInvalidData) */
+    {"object ID + separate bitangent", PhongGL::Flag::ObjectId|PhongGL::Flag::Bitangent, 1},
     {"instanced object ID", PhongGL::Flag::InstancedObjectId, 1},
     {"object ID + alpha mask + specular texture", PhongGL::Flag::ObjectId|PhongGL::Flag::AlphaMask|PhongGL::Flag::SpecularTexture, 1},
     #endif