https://bugs.webkit.org/show_bug.cgi?id=94834
PR #197662

Reviewed by Rob Buis.
Patch by Antonio Gomes <agomes@rim.com>
Internally reviewed by Arvid Nilsson.

In order to be able to remove a bunch of obsolete code from
InRegionScroller.cpp, we need to unify the codepaths for slow
and fast in-region scrolling.

This patch caches the root scrollable node of each scrollable block
in InRegionScrollableArea also for the non-composited-scrolling case now too
(analogly to the way we cache LayerWebKitThread for the composited scrolling case).

Now the client (libwebview) can dispatch an in-region scrolling with one single code path,
making use of a boolean (argh!) to inform if the scroll of the given
layer supports compositing or not. Later on, this boolean is used to casting the proper element.

* Api/InRegionScroller.cpp:
(BlackBerry::WebKit::InRegionScroller::setScrollPositionWebKitThread):
(BlackBerry::WebKit::InRegionScrollerPrivate::setScrollPositionWebKitThread):
* Api/InRegionScroller.h:
* Api/InRegionScroller_p.h:
(InRegionScrollerPrivate):
* WebKitSupport/InRegionScrollableArea.cpp:
(WebKit):
(BlackBerry::WebKit::InRegionScrollableArea::InRegionScrollableArea):
(BlackBerry::WebKit::enclosingLayerNode):
* WebKitSupport/InRegionScrollableArea.h:
(WebCore):
(InRegionScrollableArea):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@126474 268f45cc-cd09-0410-ab3c-d52691b4dbfc