This is not a regression, and probably not a visible bug fix either. On the other hand, it is a clear bug fix, and a relatively safe one as well. I don't know whether it makes more sense to defer this until after code freeze.
-- v2: wined3d: Use a string channel desc to initialize typed formats. wined3d: Separate a parse_channel_desc() helper. d3d10core/tests: Add a basic test for vertex formats. d3d11/tests: Add a basic test for vertex formats.