On mobile, tapping on region comments doesn't open the comment dialog. This

happens because touch events are being swallowed by the _onMouseDown

handler, which doesn't handle clicks. Now we explicitly handle touchend

events with the onClick handler which will bubble up the event to open

the comment dialog. And the comment dialog doesn't open upon resizing or

moving the comment, which matches desktop behaviour.
I also made sure that our text based comments don't have this problem.

Tested the following on mobile and desktop:

- Creating new comments

- Moving, resizing and clicking on existing draft comments

- Trying to move/resize existing published comments.

- Clicking on existing published comments.