Multi-byte characters in text file are garbled when previewing it in a page

Summary

Multi-byte characters in text file are garbled when previewing it in a page.

Steps to Reproduce

1. Create a page
2. Drag/Drop a text file (.txt) to the page when editing the page
3. Save the page
4. Click the text file in the page and preview it

Expected Results

Multi-byte characters in the text file should be shown correctly.

Actual Results

Multi-byte characters in the text file were garbled as follows.

Notes

Previewing text file seems to be Cloud Only feature at this moment. (Please see CONF-36508 for the details.)

Workaround

Right click the text file in the page and use "Open link in New Tab" feature provided by browser instead.