fix(package.json): Add missing polyfill dependency.

Author: halfzebra

package.json

@@ -44,6 +44,7 @@
     "minimist": "1.2.0",
     "postcss-flexbugs-fixes": "^3.3.0",
     "postcss-loader": "2.1.5",
+    "promise": "8.0.1",
     "prompt": "1.0.0",
     "react-dev-utils": "6.0.0-next.3e165448",
     "react-error-overlay": "^4.0.0",