Update css loader (facebook#1057)

* Update css-loader to 0.26.0

* Update the production webpack config

Author: nhajidin

Diff for: packages/react-scripts/config/webpack.config.prod.js

@@ -142,15 +142,7 @@ module.exports = {
       // in the main CSS file.
       {
         test: /\.css$/,
-        // "?-autoprefixer" disables autoprefixer in css-loader itself:
-        // https://github.com/webpack/css-loader/issues/281
-        // We already have it thanks to postcss. We only pass this flag in
-        // production because "css" loader only enables autoprefixer-powered
-        // removal of unnecessary prefixes when Uglify plugin is enabled.
-        // Webpack 1.x uses Uglify plugin as a signal to minify *all* the assets
-        // including CSS. This is confusing and will be removed in Webpack 2:
-        // https://github.com/webpack/webpack/issues/283
-        loader: ExtractTextPlugin.extract('style', 'css?importLoaders=1&-autoprefixer!postcss')
+        loader: ExtractTextPlugin.extract('style', 'css?importLoaders=1!postcss')
         // Note: this won't work without `new ExtractTextPlugin()` in `plugins`.
       },
       // JSON is not enabled by default in Webpack but both Node and Browserify

Diff for: packages/react-scripts/package.json

@@ -33,7 +33,7 @@
     "chalk": "1.1.3",
     "connect-history-api-fallback": "1.3.0",
     "cross-spawn": "4.0.2",
-    "css-loader": "0.25.0",
+    "css-loader": "0.26.0",
     "detect-port": "1.0.1",
     "dotenv": "2.0.0",
     "eslint": "3.8.1",