fixup! Add Tizen-platform implementation of RenderViewObserver
fixup! Add Tizen-platform implementation of RenderViewObserver

Adds internal pointer validation for WebNode objects.
In file render_view_observer_efl.cc, object WebNode is intensively used.
Its methods call is usually using corresponding calls of internal Node pointer.
Since class WebNode has default constructor it can have this internal pointer
uninitialized. It was the main cause of the crash in taping cases. Adding
validation of this internal Node pointer in function DoHitTest() (using
WebNode::isNull() method), solved problem.

This is a cherry-pick of the following patch:
http://165.213.202.130:8080/#/c/68604/ by Sergiy Prutskov

Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=9525
Reviewed by: Antonio Gomes, Piotr Tworek

Change-Id: Ib623ae17bb658c9871c20a40545f83de292a5038
Signed-off-by: Tomasz Czekala <f86e7ecac0481bba6eb13b4e3bfa907080335132@partner.samsung.com>

crosswalk-project/chromium-efl,hgl888/chromium-efl,hgl888/chromium-efl,crosswalk-project/chromium-efl,hgl888/chromium-efl,hgl888/chromium-efl,crosswalk-project/chromium-efl,crosswalk-project/chromium-efl,hgl888/chromium-efl