Add Promise polyfill in integration tests.

package-lock.json

@@ -6066,6 +6066,12 @@
         "event-emitter": "~0.3.5"
       }
     },
+    "es6-promise": {
+      "version": "4.2.4",
+      "resolved": "https://registry.npmjs.org/es6-promise/-/es6-promise-4.2.4.tgz",
+      "integrity": "sha512-/NdNZVJg+uZgtm9eS3O6lrOLYmQag2DjdEXuPaHlZ6RuVqgqaVZfgYCepEIKsLqwdQArOPtC3XzRLqGGfT8KQQ==",
+      "dev": true
+    },
     "es6-set": {
       "version": "0.1.5",
       "resolved": "https://registry.npmjs.org/es6-set/-/es6-set-0.1.5.tgz",

package.json

@@ -29,6 +29,7 @@
     "disc": "^1.3.3",
     "enzyme": "^3.3.0",
     "enzyme-adapter-react-16": "^1.1.1",
+    "es6-promise": "^4.2.4",
     "eslint": "^3.19.0",
     "eslint-config-standard": "^10.2.1",
     "eslint-config-standard-preact": "^1.1.6",

test/endtoend/src/main.js

@@ -1,3 +1,4 @@
+require('es6-promise/auto')
 const Uppy = require('@uppy/core')
 const DragDrop = require('@uppy/drag-drop')
 const Dashboard = require('@uppy/dashboard')