Merge pull request #2582 from LLK/greenkeeper/react-virtualized-9.20.1

Update react-virtualized to the latest version 

package.json

@@ -90,7 +90,7 @@
     "react-tabs": "2.2.2",
     "react-test-renderer": "16.2.0",
     "react-tooltip": "3.6.1",
-    "react-virtualized": "9.20.0",
+    "react-virtualized": "9.20.1",
     "redux": "3.7.2",
     "redux-mock-store": "^1.2.3",
     "redux-throttle": "0.1.1",