Fix bad caret position with horizontal scrolling

Fix bad caret position with horizontal scrolling

Horizontal scrolling used to be taken into account when updating caret
geometry. This is wrong since it may have changed when time comes to
draw the caret. This leads to a situation where the first apparition
of the caret is at a wrong place.

Now the extra horizontal offset is used at drawing time.

Fixes bug #11603.

(cherry picked from commit bdf58b77e7bebce6e9554151a909a5ee62be439f)