https://bugs.webkit.org/show_bug.cgi?id=97922
PR #197093

Reviewed by Yong Li.
Patch by Antonio Gomes <agomes@rim.com>
Internaly reviewed by Arvid Nilsson.

Add support for composited scrolling in a inner frame level:

1) When creating an InRegionScrollableArea, for a inner scrollable frame,
cache and camouflag the appropriated scroll layer (i.e. RenderLayerCompositor::scrollLayer);

2) Differentiate what type of scroll target we are at: BlockElement or
InnerFrame;

3) Change the signature of the public methods to support and newly passed
in ScrollTarget parameter;
As a side note, this parameter is needed in order to know what class to static_cast
the GraphicsLayer::client to: in the case of a composited scrollable inner frame, the client
is a RenderLayerCompositor; in case of a composited scrollable block element, the client
is a RenderLayerBacking.

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

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@129916 268f45cc-cd09-0410-ab3c-d52691b4dbfc