Reviewed by Kevin Decker.

        https://bugs.webkit.org/show_bug.cgi?id=33455
        Allows plugins to participate in accelerated compositing

        For plugins using the CoreAnimation rendering mode, host their CALayers in the
        accelerated compositing layer tree.

        This requires making normal flow RenderLayers for RenderEmbeddedObjects when they represent
        a plugin using this mode.

        * WebCore.base.exp: Export Node::setNeedsStyleRecalc() for use by WebKit.
        * WebCore.xcodeproj/project.pbxproj: Re-order files for sorting.

        * rendering/RenderEmbeddedObject.h:
        * rendering/RenderEmbeddedObject.cpp:
        (WebCore::RenderEmbeddedObject::requiresLayer): Make a layer if the plugin is using
        accelerated compositing mode.
        (WebCore::RenderEmbeddedObject::allowsAcceleratedCompositing): Asks whether the plugin has
        a layer, via PluginWidget.

        * rendering/RenderLayer.cpp:
        (WebCore::RenderLayer::shouldBeNormalFlowOnly):
        (WebCore::RenderLayer::isSelfPaintingLayer):
        RenderEmbeddedObjects should be normal flow layers, and self-painting layers.

        * rendering/RenderLayerBacking.cpp:
        (WebCore::RenderLayerBacking::updateGraphicsLayerConfiguration):
        Parent the plugin's layer in the GraphicsLayer when updating the layer configuration.

        * rendering/RenderLayerCompositor.h:
        * rendering/RenderLayerCompositor.cpp:
        (WebCore::RenderLayerCompositor::requiresCompositingLayer):
        (WebCore::RenderLayerCompositor::requiresCompositingForPlugin):
        RenderEmbeddedObjects that allow accelerated compositing trip accelerated compositing mode
        for the page.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@53110 268f45cc-cd09-0410-ab3c-d52691b4dbfc