[EFL] Arrow of combo box are drawn twice
https://bugs.webkit.org/show_bug.cgi?id=113917

Reviewed by Gyuyoung Kim.

combo_button_icon part is for arrow so that images of combo_button part should
not contain arrow.

No new tests required due to no behavioral change.

* platform/efl/DefaultTheme/widget/combo/combo_focus_button.png:
* platform/efl/DefaultTheme/widget/combo/combo_hover_button.png:
* platform/efl/DefaultTheme/widget/combo/combo_press_button.png:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148787 268f45cc-cd09-0410-ab3c-d52691b4dbfc