Fix URLs visited during private browsing showing up in WebpageIcons.db.

Fix URLs visited during private browsing showing up in WebpageIcons.db.

Ported from http://trac.webkit.org/changeset/181565 by beidson@apple.com.

Upstream patch by Sam Weinig, reviewed by Brady Eidson.

* loader/icon/IconController.cpp:

(WebCore::IconController::startLoader): Bail early here if the page is using an ephemeral session.
(WebCore::IconController::continueLoadWithDecision): Instead of here.

Change-Id: I263bb6122606caa3488d641b127dd377012ee424
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
Gbp-Pq: Name webpageicons_db_privacy.patch