Remove es6-map and es6-set infavour of existing core-js

app/assets/javascripts/test_utils/index.js

-import 'es6-map/implement';
-import 'es6-set/implement';
+import 'core-js/es6/map';
+import 'core-js/es6/set';
 import simulateDrag from './simulate_drag';
 
 // Export to global space for rspec to use

package.json

@@ -28,8 +28,6 @@
     "document-register-element": "^1.3.0",
     "dropzone": "^4.2.0",
     "emoji-unicode-version": "^0.2.1",
-    "es6-map": "^0.1.5",
-    "es6-set": "^0.1.5",
     "eslint-plugin-html": "^2.0.1",
     "exports-loader": "^0.6.4",
     "file-loader": "^0.11.1",

yarn.lock

@@ -1887,7 +1887,7 @@ es6-iterator@2, es6-iterator@~2.0.1:
     es5-ext "^0.10.14"
     es6-symbol "^3.1"
 
-es6-map@^0.1.3, es6-map@^0.1.5:
+es6-map@^0.1.3:
   version "0.1.5"
   resolved "https://registry.yarnpkg.com/es6-map/-/es6-map-0.1.5.tgz#9136e0503dcc06a301690f0bb14ff4e364e949f0"
   dependencies:
@@ -1902,7 +1902,7 @@ es6-promise@^3.0.2, es6-promise@~3.0.2:
   version "3.0.2"
   resolved "https://registry.yarnpkg.com/es6-promise/-/es6-promise-3.0.2.tgz#010d5858423a5f118979665f46486a95c6ee2bb6"
 
-es6-set@^0.1.5, es6-set@~0.1.5:
+es6-set@~0.1.5:
   version "0.1.5"
   resolved "https://registry.yarnpkg.com/es6-set/-/es6-set-0.1.5.tgz#d2b3ec5d4d800ced818db538d28974db0a73ccb1"
   dependencies: