Rollup merge of #153748 - lolbinarycat:editorconfig-css, r=jieyouxu

editorconfig: css uses tabs

Tidy enforces the fact that css files use tabs, but currently `.editorconfig` says everything that isn't llvm or a Makefile should always use spaces.  This PR makes it so all editors that honor `.editorconfig` will use the correct indentation for css files.

Author: JonathanBrouwer