Fixing wrong evas_object hierarchy in eweb_view.

Fixing wrong evas_object hierarchy in eweb_view.

Previously, using |evas_object_below_get| to get the parent webview
cause warning and required addition of some defensive codes.

To prevent from warning, we should use evas_object_above_get() as
evas_object_below_get() has been misused.
This patch refactored to get the parent webView
from "evas_object_above_get", which is guided by
(https://docs.enlightenment.org/stable/efl/group__Evas__Font__Group.html)

Before the fix, evas_object_ isn't part of the EFL/Elementary layout
tree. So we needed to get value of width and height from ecore_evas.
With this patch, evas_object_ is part of the elementary layout tree.
This defensive code is no longer needed.

Original m42 patch:
- http://165.213.202.130/gerrit/#/c/87501/ .

Change-Id: I677dbde037b798773552de8473a62fdbb8b344ed
Signed-off-by: ByungJun Kim <bj1987.kim@samsung.com>