Added core-js because an error message told me to

rpg-docs/package-lock.json

@@ -75,7 +75,7 @@
       "version": "https://registry.npmjs.org/babel-runtime/-/babel-runtime-6.23.0.tgz",
       "integrity": "sha1-CpSJ8UTecO+zzkMArM2zKeL8VDs=",
       "requires": {
-        "core-js": "https://registry.npmjs.org/core-js/-/core-js-2.4.1.tgz",
+        "core-js": "2.5.1",
         "regenerator-runtime": "https://registry.npmjs.org/regenerator-runtime/-/regenerator-runtime-0.10.5.tgz"
       }
     },
@@ -165,8 +165,9 @@
       "integrity": "sha1-PXz0Rk22RG6mRL9LOVB/mFEAjo4="
     },
     "core-js": {
-      "version": "https://registry.npmjs.org/core-js/-/core-js-2.4.1.tgz",
+      "version": "2.5.1",
-      "integrity": "sha1-TekR5mew6ukSTjQlS1OupvxhjT4="
+      "resolved": "https://registry.npmjs.org/core-js/-/core-js-2.5.1.tgz",
+      "integrity": "sha1-rmh03GaTd4m4B1T/VCjfZoGcpQs="
     },
     "core-util-is": {
       "version": "1.0.2",

rpg-docs/package.json

@@ -14,6 +14,7 @@
     "@polymer/polymer": "^1.2.5-npm-test.2",
     "babel-runtime": "^6.23.0",
     "bcrypt": "^1.0.3",
-    "bower": "^1.7.9"
+    "bower": "^1.7.9",
+    "core-js": "^2.5.1"
   }
 }