Have Position deal with more references

Source/core/editing/FormatBlockCommand.cpp

 /*
  * Copyright (C) 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 70 matching lines @@
         nodeAfterInsertionPosition = refNode;
     }
 
     if (!blockNode) {
         // Create a new blockquote and insert it as a child of the root editable element. We accomplish
         // this by splitting all parents of the current paragraph up to that point.
         blockNode = createBlockElement();
         insertNodeBefore(blockNode, nodeAfterInsertionPosition);
     }
 
-    Position lastParagraphInBlockNode = blockNode->lastChild() ? positionAfterNode(blockNode->lastChild()) : Position();
+    Position lastParagraphInBlockNode = blockNode->lastChild() ? positionAfterNode(*blockNode->lastChild()) : Position();
     bool wasEndOfParagraph = isEndOfParagraph(VisiblePosition(lastParagraphInBlockNode));
 
     moveParagraphWithClones(VisiblePosition(start), VisiblePosition(end), blockNode.get(), outerBlock.get());
 
     // Copy the inline style of the original block element to the newly created block-style element.
     if (outerBlock.get() != nodeAfterInsertionPosition.get() && toHTMLElement(nodeAfterInsertionPosition.get())->hasAttribute(styleAttr))
         blockNode->setAttribute(styleAttr, toHTMLElement(nodeAfterInsertionPosition.get())->getAttribute(styleAttr));
 
     if (wasEndOfParagraph && !isEndOfParagraph(VisiblePosition(lastParagraphInBlockNode)) && !isStartOfParagraph(VisiblePosition(lastParagraphInBlockNode)))
         insertBlockPlaceholder(lastParagraphInBlockNode);
@@ skipping 58 matching lines @@
             return n;
         if (isBlock(n))
             lastBlock = n;
         if (isListElement(n))
             return n->parentNode()->rendererIsEditable() ? n->parentNode() : n;
     }
     return lastBlock;
 }
 
 }