Add promise polyfill

client/package.json

@@ -49,6 +49,7 @@
     "autolinker": "^1.4.3",
     "backo": "^1.1.0",
     "base64-arraybuffer": "^0.1.5",
+    "es6-promise": "^4.2.4",
     "fontfaceobserver": "^2.0.9",
     "history": "4.5.1",
     "immer": "^1.2.1",

client/src/js/index.js

@@ -1,3 +1,4 @@
+import 'es6-promise/auto';
 import React from 'react';
 import { render } from 'react-dom';
 

client/yarn.lock

@@ -2512,7 +2512,7 @@ es-to-primitive@^1.1.1:
     is-date-object "^1.0.1"
     is-symbol "^1.0.1"
 
-es6-promise@^4.1.1:
+es6-promise@^4.1.1, es6-promise@^4.2.4:
   version "4.2.4"
   resolved "https://registry.yarnpkg.com/es6-promise/-/es6-promise-4.2.4.tgz#dc4221c2b16518760bd8c39a52d8f356fc00ed29"