refactor postcss-custom-properties and cleanup in postcss-preset-env#603

romainmenke merged 13 commits intopostcss-preset-env--v8csstools/postcss-plugins:postcss-preset-env--v8from

postcss-custom-properties--rational-emu-e1e1979101csstools/postcss-plugins:postcss-custom-properties--rational-emu-e1e1979101Copy head branch name to clipboard