Make VisiblePosition::characterAfter() not to use Position::containerText()

Source/core/editing/VisiblePosition.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Portions Copyright (c) 2011 Motorola Mobility, 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
@@ skipping 641 matching lines @@
     }
 
     // When not at a line wrap, make sure to end up with DOWNSTREAM affinity.
     if (!inSameLine(PositionWithAffinityTemplate<Strategy>(deepPosition, DOWNSTREAM), PositionWithAffinityTemplate<Strategy>(deepPosition, UPSTREAM)))
         return;
     m_affinity = DOWNSTREAM;
 }
 
 UChar32 VisiblePosition::characterAfter() const
 {
-    // We canonicalize to the first of two equivalent candidates, but the second of the two candidates
-    // is the one that will be inside the text node containing the character after this visible position.
+    // We canonicalize to the first of two equivalent candidates, but the second
+    // of the two candidates is the one that will be inside the text node
+    // containing the character after this visible position.
     Position pos = m_deepPosition.downstream();
-    if (!pos.containerNode() || !pos.containerNode()->isTextNode() || !pos.isOffsetInAnchor())
+    if (!pos.isOffsetInAnchor())
+        return 0;
+    Node* containerNode = pos.containerNode();
+    if (!containerNode || !containerNode->isTextNode())
         return 0;
     unsigned offset = static_cast<unsigned>(pos.offsetInContainerNode());
-    Text* textNode = pos.containerText();
+    Text* textNode = toText(containerNode);
     unsigned length = textNode->length();
     if (offset >= length)
         return 0;
 
     return textNode->data().characterStartingAt(offset);
 }
 
 LayoutRect VisiblePosition::localCaretRect(LayoutObject*& layoutObject) const
 {
     PositionWithAffinity positionWithAffinity(m_deepPosition, m_affinity);
@@ skipping 82 matching lines @@
     else
         fprintf(stderr, "Cannot showTree for (nil) VisiblePosition.\n");
 }
 
 void showTree(const blink::VisiblePosition& vpos)
 {
     vpos.showTreeForThis();
 }
 
 #endif