Introduce EditingAlgorithm<Traversal> class

Source/core/editing/htmlediting.h

 /*
  * Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 67 matching lines @@
 Element* isFirstPositionAfterTable(const VisiblePosition&);
 
 // offset functions on Node
 
 int lastOffsetForEditing(const Node*);
 int caretMinOffset(const Node*);
 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.
 
 // Returns true for nodes that either have no content, or have content that is ignored (skipped over) while editing.
 // 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)
 {
     return !node->isTextNode() && node->canContainRangeEndPoint();
 }
 
 bool isAtomicNode(const Node*);
 bool isBlock(const Node*);
 bool isInline(const Node*);
@@ skipping 147 matching lines @@
     // FIXME: this is required until 6853027 is fixed and text checking can do this for us.
     return character == '\'' || character == rightSingleQuotationMark || character == hebrewPunctuationGershayim;
 }
 
 String stringWithRebalancedWhitespace(const String&, bool startIsStartOfParagraph, bool endIsEndOfParagraph);
 const String& nonBreakingSpaceString();
 
 }
 
 #endif