Move stub implementations of ScrollingCoordinator functions into ScrollingCoordinator...

Move stub implementations of ScrollingCoordinator functions into ScrollingCoordinatorNone.cpp
https://bugs.webkit.org/show_bug.cgi?id=78951

Reviewed by Adam Barth.

This move stubs for ScrollingCoordinator functions into ScrollingCoordinatorNone.cpp instead of #ifdefing inside
ScrollingCoordinator.cpp.  The mac port uses ScrollingCoordinator when #if ENABLE(THREADED_SCROLLING) is not set
and implementations in ScrollingCoordinator.cpp / ScrollingCoordinatorMac.mm otherwise.  The chromium port
always uses implementations in ScrollingCoordinatorChromium.cpp.  All other ports use
ScrollingCoordinatorNone.cpp.

* CMakeLists.txt:
* GNUmakefile.list.am:
* Target.pri:
* WebCore.vcproj/WebCore.vcproj:
* WebCore.xcodeproj/project.pbx:
* page/scrolling/ScrollingCoordinator.cpp:
* page/scrolling/ScrollingCoordinatorNone.cpp:
(WebCore):
(WebCore::ScrollingCoordinator::create):
(WebCore::ScrollingCoordinator::frameViewHorizontalScrollbarLayerDidChange):
(WebCore::ScrollingCoordinator::frameViewVerticalScrollbarLayerDidChange):
(WebCore::ScrollingCoordinator::setScrollLayer):
(WebCore::ScrollingCoordinator::setNonFastScrollableRegion):
(WebCore::ScrollingCoordinator::setScrollParameters):
(WebCore::ScrollingCoordinator::setWheelEventHandlerCount):
(WebCore::ScrollingCoordinator::setShouldUpdateScrollLayerPositionOnMainThread):
* page/scrolling/mac/ScrollingCoordinatorMac.mm:
(WebCore::ScrollingCoordinator::create):
(WebCore):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108202 268f45cc-cd09-0410-ab3c-d52691b4dbfc