Introduce composed tree version of canonicalPosition() in VisiblePosition

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 110 matching lines @@
 bool isBlockFlowElement(const Node&);
 TextDirection directionOfEnclosingBlock(const Position&);
 
 // -------------------------------------------------------------------------
 // Position
 // -------------------------------------------------------------------------
 
 // Functions returning Position
 
 Position nextCandidate(const Position&);
+PositionInComposedTree nextCandidate(const PositionInComposedTree&);
 Position previousCandidate(const Position&);
+PositionInComposedTree previousCandidate(const PositionInComposedTree&);
 
 Position nextVisuallyDistinctCandidate(const Position&);
 Position previousVisuallyDistinctCandidate(const Position&);
 
 Position positionBeforeContainingSpecialElement(const Position&, HTMLElement** containingSpecialElement = nullptr);
 Position positionAfterContainingSpecialElement(const Position&, HTMLElement** containingSpecialElement = nullptr);
 
 inline Position firstPositionInOrBeforeNode(Node* node)
 {
     return Position::firstPositionInOrBeforeNode(node);
@@ skipping 69 matching lines @@
 // Element
 // -------------------------------------------------------------------------
 
 // Functions returning Element
 
 PassRefPtrWillBeRawPtr<HTMLSpanElement> createTabSpanElement(Document&);
 PassRefPtrWillBeRawPtr<HTMLSpanElement> createTabSpanElement(Document&, const String& tabText);
 PassRefPtrWillBeRawPtr<HTMLBRElement> createBlockPlaceholderElement(Document&);
 
 Element* editableRootForPosition(const Position&, EditableType = ContentIsEditable);
+Element* editableRootForPosition(const PositionInComposedTree&, EditableType = ContentIsEditable);
 Element* unsplittableElementForPosition(const Position&);
 
 // Boolean functions on Element
 
 bool canMergeLists(Element* firstList, Element* secondList);
 
 // -------------------------------------------------------------------------
 // VisibleSelection
 // -------------------------------------------------------------------------
 
@@ skipping 22 matching lines @@
     // FIXME: this is required until 6853027 is fixed and text checking can do this for us.
     return character == '\'' || character == rightSingleQuotationMarkCharacter || character == hebrewPunctuationGershayimCharacter;
 }
 
 String stringWithRebalancedWhitespace(const String&, bool startIsStartOfParagraph, bool endIsEndOfParagraph);
 const String& nonBreakingSpaceString();
 
 }
 
 #endif