Re-implement didCreateScriptContext to RenderFrameObserverEfl.

Re-implement didCreateScriptContext to RenderFrameObserverEfl.

DidCreateScriptContext and WillReleaseScriptContext are moved
to ContentRendererClient by (1),(2) in opensource.

DidCreateScriptContext and WillReleaseScriptContext are called
when calling open/close window by javascript.
Those functions must be called together.

In case of m47 chromium-efl, we do not call DidCreateScriptContext.
For this reason, renderer process is crashed when
javascript context is released from injected_bundle.

This patch has 2 modifications as below.
- Remove |WillReleaseScriptContext| from ContentRendererClientEfl.
- Move |didCreateScriptContext| to RenderFrameObserverEfl.

(1) https://codereview.chromium.org/1040403003
(2) https://codereview.chromium.org/185713008

Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=15036

Reviewed by: a.renevier, a1.gomes, djmix.kim, g.czajkowski, msu.koo

Change-Id: I008937710d08472a6cfb77a51b1cbf01ffacc221
Signed-off-by: DongJun Kim <djmix.kim@samsung.com>