Remove dependency used for PhantomJS previously

cburgmer · cburgmer · commit c5b609c52e89 · 2018-03-18T20:20:01.000+01:00
diff --git a/package.json b/package.json
@@ -31,7 +31,6 @@
     "sane-domparser-error": "~0.2.0"
   },
   "devDependencies": {
-    "es6-promise": "^4.0.5",
     "grunt": "^1.0.0",
     "grunt-browserify": "^5.0.0",
     "grunt-cli": "^1.0.0",
