An option to skip vendor/gem assets

[tadast]

Should there be a way to skip vendor and gem assets? In one of my projects a lot of CSS comes from vendor assets and gems (e.g. engines, such as tolk). All of them are processed by autoprefixer by default. Most of the gems and assets usually have their css with prefixes already.

You can also have admin dashboards etc where you control what browsers are used and there's no need to add prefixes to these CSS files

Main motivation: performance. Based on my benchmarks I could shave off ~5s (out of 20s) by being able to omit certain CSS files that don't need auto-prefixing.

What would be your thoughts about this?

[ai]

I think that it is always good to update their prefixes according to your target browsers.

But we can do it for development. Please, send PR with an option which will disable prefixing for gems on Rails.env.development?