ubrowser: Fix EFL error trigger by incorrect call to elm focus_set func.

ubrowser: Fix EFL error trigger by incorrect call to elm focus_set func.

Technically the Ewk WebView object is not an elementary widget. Its a
smart object build from elementary widgets. We should not pass the
object to any elm function calls as they will only trigger runtime
errors without doing anything.

This patch fixes the following runtime EFL error message seen during
ubrowser startup:

  ERR<18221>:eo lib/eo/eo.c:676 _eo_call_resolve() in elm_widget.eo.c:111:
      func 'elm_obj_widget_can_focus_set' (304) could not be resolved for
      class 'Evas_Object_Smart'.

Change-Id: I8d3587c72dd911648a431a2f822b5806b634e36f
Signed-off-by: Piotr Tworek <p.tworek@samsung.com>