This is in preparation to vanilla's new system theme.
Makes the default theme an actual theme instead of relying on loading core assets.
Changes some checks for "default" to "system"
This is also more of a proof of concept.
I'm not sure how upstream intends to deal with it.
Another alternative would be to refactor the theming system to support multiple pseudo-skins.
This is however simpler, though I'm not convinced by this.
This is in preparation to vanilla's new system theme.
Makes the default theme an actual theme instead of relying on loading core assets.
Changes some checks for "default" to "system"
This is also more of a proof of concept. I'm not sure how upstream intends to deal with it. Another alternative would be to refactor the theming system to support multiple pseudo-skins. This is however simpler, though I'm not convinced by this.