feat: build.autoprefixer option

allows enable/disable or customize autoprefixer

closes #1296

lib/builder/webpack/base.config.js

@@ -18,13 +18,9 @@ import { styleLoader, extractStyles } from './helpers'
 export default function webpackBaseConfig ({ isClient, isServer }) {
   const nodeModulesDir = join(__dirname, '..', 'node_modules')
 
-  /* istanbul ignore if */
-  if (!Array.isArray(this.options.build.postcss)) {
-    this.options.build.postcss = [
-      autoprefixer({
-        browsers: ['last 3 versions']
-      })
-    ]
+  // Enable autoprefixer if both autoprefixer postcss are enabled
+  if (this.options.build.autoprefixer && Array.isArray(this.options.build.postcss)) {
+    this.options.build.postcss.push(autoprefixer(this.options.build.autoprefixer))
   }
 
   const config = {

lib/common/options.js

@@ -115,7 +115,10 @@ Options.defaults = {
     vendor: [],
     plugins: [],
     babel: {},
-    postcss: undefined,
+    autoprefixer: {
+      browsers: ['last 3 versions']
+    },
+    postcss: [],
     templates: [],
     watch: [],
     devMiddleware: {},