fix(package): update dompurify to version 0.8.9

Closes #2339

package.json

@@ -183,7 +183,7 @@
     "common-tags": "1.4.0",
     "config": "1.25.1",
     "deep-eql": "2.0.1",
-    "dompurify": "0.8.7",
+    "dompurify": "0.8.9",
     "es6-error": "4.0.2",
     "express": "4.15.2",
     "extract-text-webpack-plugin": "1.0.1",