https://bugs.webkit.org/show_bug.cgi?id=96706

Reviewed by Simon Fraser.

Source/WebCore: 

Replaced suspendWidgetHierarchyUpdates and resumeWidgetHierarchyUpdates by WidgetHierarchyUpdatesSuspensionScope.

* WebCore.exp.in: Export new symbols.
* dom/ContainerNode.cpp:
(WebCore::ContainerNode::removeChild):
(WebCore::ContainerNode::removeChildren):
* dom/Document.cpp:
(WebCore::Document::recalcStyle):
* dom/Element.cpp:
(WebCore::Element::attach):
(WebCore::Element::detach):
* page/mac/EventHandlerMac.mm:
(WebCore::EventHandler::passMouseDownEventToWidget):
* rendering/RenderWidget.cpp:
(WebCore):
(WebCore::WidgetHierarchyUpdatesSuspensionScope::widgetNewParentMap):
(WebCore::WidgetHierarchyUpdatesSuspensionScope::moveWidgets):
(WebCore::moveWidgetToParentSoon):
* rendering/RenderWidget.h:
(WidgetHierarchyUpdatesSuspensionScope):
(WebCore::WidgetHierarchyUpdatesSuspensionScope::WidgetHierarchyUpdatesSuspensionScope):
(WebCore::WidgetHierarchyUpda...