Fix lack of ergonomy in Chrome HTML textarea in Note creation

Customer has detected a problem of input in the HTML textarea with Chrome new versions of browser.

How to reproduce:

1. create a new Note document
2. Clic in the middle of the HTML zone to enter text => nothing happens (no cursor, no keyboard input)
3. Place the mouse nearby the top of the input zone ("first line"), and clic there => It is then possible to enter text
4. enter a title and save
5. modify the document
6. a clic anywhere in the HTM zone enables to enter text straightaway

It is only reproduced in Chrome recent versions of browser.