GWT: X.X: fix back to text highlight padding

Some edition are sensible to spaces between words (ex: GRAAL). Currently the highlight padding is set to 3px left and right.

Solution

step 1
set the left and right padding to 0px.
(keep 3px top and bottom)

step 2 : the word is resized because of the padding, find a better CSS solution to highlight the word ?

(from redmine: issue id 1217, created on 2015/01/07 by Matthieu Decorde)