Mark Supplement instead of RefCountedSupplement in NavigatorContentUtils
https://bugs.webkit.org/show_bug.cgi?id=132151

Reviewed by Darin Adler.

Though Original goal was to make it sharable across navigator instances, the NavigatorContentUtils
has used RefCountedSupplement<Page> instead of RefCountedSupplement<Navigator>. This patch makes it
use Supplement<Page> because there is no scenario which needs to be shared across navigator instances.

Blink merge from https://src.chromium.org/viewvc/blink?view=rev&revision=171403.

No new tests, no behavior changes.

* Modules/navigatorcontentutils/NavigatorContentUtils.cpp:
(WebCore::NavigatorContentUtils::from):
(WebCore::NavigatorContentUtils::create):
(WebCore::provideNavigatorContentUtilsTo):
* Modules/navigatorcontentutils/NavigatorContentUtils.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@167789 268f45cc-cd09-0410-ab3c-d52691b4dbfc