When typing in a textarea, with the cursor position at the end of the textarea, typing the Return key adds two LF chars to the textarea content. Only one LF char is displayed. The duplicated character gets apparently added at the end, after the cursor, and gets overwritten by the next keystroke.
Created attachment 25009 [details] Web page with a textarea to test and reproduce the bug Save this web page and open it with Safari. It contains a textarea to test and reproduce the bug.