Make Document::nodeChildrenWillBeRemoved() take a reference

Source/core/dom/ContainerNode.cpp

Index: Source/core/dom/ContainerNode.cpp
diff --git a/Source/core/dom/ContainerNode.cpp b/Source/core/dom/ContainerNode.cpp
index 454fb9a7c9103cdf4f2de134cf58d5fe4160dffb..b74558de27e07a893df67239ee6e75f8cbd51790 100644
--- a/Source/core/dom/ContainerNode.cpp
+++ b/Source/core/dom/ContainerNode.cpp
@@ -528,7 +528,7 @@ void ContainerNode::removeChildren()
         document().removeFocusedElementOfSubtree(this, true);
 
         // Removing a node from a selection can cause widget updates.
-        document().nodeChildrenWillBeRemoved(this);
+        document().nodeChildrenWillBeRemoved(*this);
     }