Bump rollup from 1.27.7 to 1.27.9 (#419)

Bump rollup from 1.27.7 to 1.27.9

package.json

@@ -85,7 +85,7 @@
     "nodemon": "^2.0.1",
     "npm-run-all": "4.1.5",
     "postcss-cli": "6.1.3",
-    "rollup": "1.27.7",
+    "rollup": "1.27.9",
     "rollup-plugin-babel": "4.3.3",
     "rollup-plugin-babel-minify": "9.1.1",
     "rollup-plugin-commonjs": "10.1.0",