Rename descendentxxx to descendantxxxx in RenderLayerBacking

Rename descendentxxx to descendantxxxx in RenderLayerBacking
https://bugs.webkit.org/show_bug.cgi?id=140979

Patch by Jeongmin Kim <jm86.kim@lge.com> on 2015-01-28
Reviewed by Martin Robinson.

Rename descendentxxx to descendantxxxx in RenderLayerBacking
for matching other variables and function names.

* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::updateConfiguration):
(WebCore::RenderLayerBacking::updateAfterDescendants):
(WebCore::RenderLayerBacking::updateChildClippingStrategy):
(WebCore::RenderLayerBacking::paintsChildren):
(WebCore::descendantLayerPaintsIntoAncestor):
(WebCore::RenderLayerBacking::isPaintDestinationForDescendantLayers):
(WebCore::descendentLayerPaintsIntoAncestor): Deleted.
(WebCore::RenderLayerBacking::isPaintDestinationForDescendentLayers): Deleted.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@179244 268f45cc-cd09-0410-ab3c-d52691b4dbfc