[EFL] LayoutTestController needs implementation of goBack

[EFL] LayoutTestController needs implementation of goBack
https://bugs.webkit.org/show_bug.cgi?id=81914

Patch by Christophe Dumez <christophe.dumez@intel.com> on 2012-04-03
Reviewed by Philippe Normand.

Tools:

Implement goBack() in EFL's LayoutTestController by calling
ewk_frame_back().

* DumpRenderTree/efl/LayoutTestControllerEfl.cpp:
(LayoutTestController::goBack):

LayoutTests:

Unskip loader/navigation-while-deferring-loads test in EFL now that
its LayoutTestController supports goBack().

* platform/efl/Skipped:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@113015 268f45cc-cd09-0410-ab3c-d52691b4dbfc