This is a cherry-pick of the following commits:

  688a5063
  b4c77eb6
  0e7a938a
  ff8b17d3
  b8ca346a

The original one was done to fix bug #530656 but was then reverted
in 55a8fead after the tinymce
autoresize plugin was enabled.

However, the autoresize plugin was removed after causing problems
in bug #791854 (see 651fcdba

) so
we'll restore this work-around for the time being.

Change-Id: I74176a3a155a7d9442448d09f206250b55394611
Signed-off-by: Francois Marier <francois@catalyst.net.nz>