feat: upgrade css loader to v2 (#4503)

* use new exportOnlyLocals option

* upgrade css-loader in package.json

packages/webpack/package.json

@@ -18,7 +18,7 @@
     "caniuse-lite": "^1.0.30000916",
     "chalk": "^2.4.1",
     "consola": "^2.3.0",
-    "css-loader": "^1.0.1",
+    "css-loader": "^2.0.0",
     "cssnano": "^4.1.7",
     "file-loader": "^2.0.0",
     "fs-extra": "^7.0.1",

packages/webpack/src/utils/style-loader.js

@@ -64,8 +64,11 @@ export default class StyleLoader {
   }
 
   css(options) {
+    if (this.isServer && this.extractCSS) {
+      options.exportOnlyLocals = true
+    }
     return {
-      loader: (this.isServer && this.extractCSS) ? 'css-loader/locals' : 'css-loader',
+      loader: 'css-loader',
       options
     }
   }