Missing css in CompressionPlugin (#3300)

Author: grizzm0

packages/angular-cli/models/webpack-build-production.ts

@@ -66,7 +66,7 @@ export const getWebpackProdConfigPartial = function(projectRoot: string,
       new CompressionPlugin({
           asset: '[path].gz[query]',
           algorithm: 'gzip',
-          test: /\.js$|\.html$/,
+          test: /\.js$|\.html$|\.css$/,
           threshold: 10240,
           minRatio: 0.8
       }),