Introduce isRenderedCharacter(Position) function

Source/core/editing/commands/InsertLineBreakCommand.cpp

 /*
  * Copyright (C) 2005, 2006 Apple Computer, 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 105 matching lines @@
         setEndingSelection(VisibleSelection(positionInParentAfterNode(*nodeToInsert), DOWNSTREAM, endingSelection().isDirectional()));
     } else if (pos.anchorNode()->isTextNode()) {
         // Split a text node
         Text* textNode = toText(pos.anchorNode());
         splitTextNode(textNode, pos.computeOffsetInContainerNode());
         insertNodeBefore(nodeToInsert, textNode);
         Position endingPosition = firstPositionInNode(textNode);
 
         // Handle whitespace that occurs after the split
         document().updateLayoutIgnorePendingStylesheets();
-        if (!endingPosition.isRenderedCharacter()) {
+        // TODO(yosin) |isRenderedCharacter()| should be removed, and we should
+        // use |VisiblePosition::characterAfter()|.
+        if (!isRenderedCharacter(endingPosition)) {
             Position positionBeforeTextNode(positionInParentBeforeNode(*textNode));
             // Clear out all whitespace and insert one non-breaking space
             deleteInsignificantTextDownstream(endingPosition);
             ASSERT(!textNode->layoutObject() || textNode->layoutObject()->style()->collapseWhiteSpace());
             // Deleting insignificant whitespace will remove textNode if it contains nothing but insignificant whitespace.
             if (textNode->inDocument()) {
                 insertTextIntoNode(textNode, 0, nonBreakingSpaceString());
             } else {
                 RefPtrWillBeRawPtr<Text> nbspNode = document().createTextNode(nonBreakingSpaceString());
                 insertNodeAt(nbspNode.get(), positionBeforeTextNode);
@@ skipping 20 matching lines @@
         // before the line break (if the line break is at the end of a block it isn't selectable).
         // So, this next call sets the endingSelection() to a caret just after the line break
         // that we inserted, or just before it if it's at the end of a block.
         setEndingSelection(endingSelection().visibleEnd());
     }
 
     rebalanceWhitespace();
 }
 
 }