Introduce EditingAlgorithm<Traversal> class

Source/core/editing/htmlediting.h

Index: Source/core/editing/htmlediting.h
diff --git a/Source/core/editing/htmlediting.h b/Source/core/editing/htmlediting.h
index 773494ab1ff57a73e78ada792c268be077feba3c..0010eb675bb381af7fa288e1a2a982d6b316c70b 100644
--- a/Source/core/editing/htmlediting.h
+++ b/Source/core/editing/htmlediting.h
@@ -85,11 +85,6 @@ int caretMaxOffset(const Node*);
 
 // boolean functions on Node
 
-inline bool isEmptyNonEditableNodeInEditable(const Node* node)
-{
-    return !node->hasChildren() && !node->hasEditableStyle() && node->parentNode() && node->parentNode()->hasEditableStyle();
-}
-
 // FIXME: editingIgnoresContent, canHaveChildrenForEditing, and isAtomicNode
 // should be renamed to reflect its usage.
 
@@ -97,7 +92,7 @@ inline bool isEmptyNonEditableNodeInEditable(const Node* node)
 // There are no VisiblePositions inside these nodes.
 inline bool editingIgnoresContent(const Node* node)
 {
-    return !node->canContainRangeEndPoint() || isEmptyNonEditableNodeInEditable(node);
+    return EditingStrategy::editingIgnoresContent(node);
 }
 
 inline bool canHaveChildrenForEditing(const Node* node)