Implement ::OnFirstUserGestureObserved and ::HideRequestAutocompleteDialog

Implement ::OnFirstUserGestureObserved and ::HideRequestAutocompleteDialog

Patch implements AutofillClientEfl's OnFirstUserGestureObserved
and HideRequestAutocompleteDialog methods by minic'ing
chrome's implementation.

First method is based on the follow comment in WebViewImpl.cpp:

"On the first input event since page load, |notifier| instructs the
autofill client to unblock values of password input fields of any forms
on the page. There is a single input event, GestureTap, which can both
be the first event after page load, and cause a form submission. In that
case, the form submission happens before the autofill client is told
to unblock the password values, and so the password values are not
submitted. To avoid that, GestureTap is handled explicitly".

Second hides an autocomplete dialog when requested. This happens on
page loads while the autocomplete is shown, etc.

As a consequence of these two methods not being unimplemented,
EWK unit tests are much less verbose too.

Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=14553

Reviewed by: a.renevier, djmix.kim, g.czajkowski, sns.park

Change-Id: I43e3b577435e240b52e67e1ef44112042b38f76a
Signed-off-by: Antonio Gomes <a1.gomes@samsung.com>