remove warning for postcss 'from' option

Author: nelsonpecora

lib/style-rewriter.js

@@ -46,13 +46,14 @@ module.exports = function (id, css, scoped, options) {
     return Promise.resolve(val)
   } else {
     var plugins = []
-    var opts = {}
+    var opts = { from: 'source' }
 
     if (options.postcss instanceof Array) {
       plugins = options.postcss.slice()
     } else if (options.postcss instanceof Object) {
       plugins = options.postcss.plugins || []
       opts = options.postcss.options
+      opts.from = opts.from || 'source'
     }
 
     // scoped css rewrite