Refactor the Text::Controller::ClearFontData.
Refactor the Text::Controller::ClearFontData.

* This method clears completely some buffers of the model.
  Then the Text::Controller::Impl::ClearModelData may access
  the same buffers out of bounds causing a crash.

Change-Id: I1b50135c707354bd3037aabb63cded10ba2e6f2f
Signed-off-by: Victor Cebollada <bd4ca07245b7f4eb2d3ace02513dff6e050d7f4b@samsung.com>

dalihub/dali-toolkit,dalihub/dali-toolkit,dalihub/dali-toolkit,dalihub/dali-toolkit