remove unused code from Utils_js
remove unused code from Utils_js

Summary: Changelog: [internal]

Reviewed By: SamChou19815

Differential Revision: D37623625

fbshipit-source-id: b5a7f6b8ba6e93b9a21dc078120a06de6909e869

facebook/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,mroch/flow,mroch/flow,mroch/flow,facebook/flow