Use tracking areas instead of (SPI) mouse moved notifications, and follow flags changes with an event monitor
https://bugs.webkit.org/show_bug.cgi?id=136564

Reviewed by Dan Bernstein.
        
WebKit1 depended on mouse moved event notifications to track mouse
moves, and on being specially called by Safari to track flags
changes. WebKit2 does both these things better - it uses a tracking area
and event monitors. Copy those approaches.

* WebKit.order: Remove reference to obsolete call.
* WebView/WebHTMLView.mm:
(-[WebHTMLViewPrivate dealloc]): No need to deallocate tracking
area, since we now just always have one.
(-[WebHTMLViewPrivate clear]): ditto
(-[WebHTMLView _postFakeMouseMovedEventForFlagsChangedEvent:]):
New method that posts a fake mouse move event in response to
a flags change event, for use by the event monitor.
(+[WebHTMLView _postFlagsChangedEvent:]): Empty this old call,
still kept around for benefit of older Safari.
(-[WebHTMLView _updateMouseoverWithEvent:]): Handle Dashboard's
special mouseover mode (previously handled in a weird way).
(-[WebHTMLView close]): No more need to mess with mouse moved observer.
(-[WebHTMLView viewWillMoveToWindow:]): ditto
(-[WebHTMLView viewDidMoveToWindow]): ditto; but now hook up a flags
changed monitor.
(-[WebHTMLView windowDidBecomeKey:]): No need to handle non-key window
tracking area or mouse moved observer.
(-[WebHTMLView windowDidResignKey:]): ditto
(-[WebHTMLView windowWillOrderOnScreen:]): No need to mess with mouse
moved observer.
(-[WebHTMLView windowWillOrderOffScreen:]): ditto
(-[WebHTMLView mouseMoved:]): Converted from the old mouseMovedNotification:
(-[WebHTMLView setDataSource:]): Change if around body to early return. Hook
up tracking area - we have to do it here, because before this point, the
WebHTMLView does not know its WebView, which is where dashboard settings
live.
(-[WebHTMLView _removeMouseMovedObserverUnconditionally]): Deleted.
(-[WebHTMLView addMouseMovedObserver]): Deleted.
(-[WebHTMLView removeMouseMovedObserver]): Deleted.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@173309 268f45cc-cd09-0410-ab3c-d52691b4dbfc