Add more Fullscreen logging

Add more Fullscreen logging
https://bugs.webkit.org/show_bug.cgi?id=189656

Reviewed by Jer Noble.

Add some fullscreen logging so I can tell whether WebFullScreenManager ever releases
the fullscreen element.

Source/WebCore:

* platform/cocoa/VideoFullscreenModelVideoElement.mm:
(VideoFullscreenModelVideoElement::VideoFullscreenModelVideoElement):
(VideoFullscreenModelVideoElement::~VideoFullscreenModelVideoElement):
(VideoFullscreenModelVideoElement::setVideoElement):

Source/WebKit:

* WebProcess/FullScreen/WebFullScreenManager.cpp:
(WebKit::WebFullScreenManager::WebFullScreenManager):
(WebKit::WebFullScreenManager::videoControlsManagerDidChange):
(WebKit::WebFullScreenManager::setPIPStandbyElement):
(WebKit::WebFullScreenManager::enterFullScreenForElement):
(WebKit::WebFullScreenManager::exitFullScreenForElement):
(WebKit::WebFullScreenManager::willEnterFullScreen):
(WebKit::WebFullScreenManager::didEnterFullScreen):
(WebKit::WebFullScreenManager::willExitFullScreen):
(WebKit::WebFullScreenManager::didExitFullScreen):
(WebKit::WebFullScreenManager::close):
* WebProcess/FullScreen/WebFullScreenManager.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@236088 268f45cc-cd09-0410-ab3c-d52691b4dbfc