False position calculation for text layers hidden textarea

[codewp]

You can view issue in below jsfiddle code, when user wants to edit text layer content inside canvas, fabricjs can not calculate right position of hidden textarea so browser scrolls up to hidden text area position.
_calcTextareaPosition function can not calculate right position of hidden text area.

https://jsfiddle.net/ajrtr1fc/

Please let me know how can I fix this issue.