chore(package): update core-js to version 3.4.5

Closes #494

Author: greenkeeper[bot]

package.json

@@ -76,7 +76,7 @@
     "@types/jquery": "^3.3.29",
     "@types/node": "~11.13.7",
     "codelyzer": "~5.0.0",
-    "core-js": "^2.5.4",
+    "core-js": "^3.4.5",
     "jasmine-core": "~3.4.0",
     "jasmine-spec-reporter": "~4.2.1",
     "karma": "~4.1.0",