fix(package): update @babel/core to version 7.7.5

Author: greenkeeper[bot]

package.json

@@ -51,7 +51,7 @@
     "polymer-workbox"
   ],
   "dependencies": {
-    "@babel/core": "7.6.2",
+    "@babel/core": "7.7.5",
     "@babel/plugin-syntax-dynamic-import": "7.2.0",
     "@babel/plugin-syntax-object-rest-spread": "7.2.0",
     "@babel/preset-env": "7.6.2",