Shift + Enter in comment box reply results in next line in post body

[cindywu]

Describe the bug
If user is owner of the post, opens reply to comment input field, hitting keyboard shortcut Shift + Enter results in next line in post body.

Steps To Reproduce

shift+enter within the comment box also applied to the main doc

Owner of post opens reply to comment box, focuses on reply input field, uses keyboard shortcut shift + enter. This results in creation of next line in post body.

Expected behavior
For any user replying to an existing comment keyboard shortcut shift + enter should move cursor to the next line. cmd + enter should result in submission of the comment.