Introduce nextPositionOf() for VisiblePosition

Source/core/editing/PlainTextRange.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov.
  *
  * 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 94 matching lines @@
         // in those cases that textRunRange is used.
         if (foundEnd) {
             // FIXME: This is a workaround for the fact that the end of a run
             // is often at the wrong position for emitted '\n's or if the
             // layoutObject of the current node is a replaced element.
             if (len == 1 && (it.text().characterAt(0) == '\n' || it.isInsideReplacedElement())) {
                 it.advance();
                 if (!it.atEnd()) {
                     textRunEndPosition = it.startPositionInCurrentContainer();
                 } else {
-                    Position runEnd = VisiblePosition(textRunStartPosition).next().deepEquivalent();
+                    Position runEnd = nextPositionOf(VisiblePosition(textRunStartPosition)).deepEquivalent();
                     if (runEnd.isNotNull())
                         textRunEndPosition = runEnd;
                 }
             }
         }
 
         if (foundStart) {
             startRangeFound = true;
             if (textRunStartPosition.computeContainerNode()->isTextNode()) {
                 int offset = start() - docTextPosition;
@@ skipping 54 matching lines @@
 
     return PlainTextRange(start, end);
 }
 
 PlainTextRange PlainTextRange::create(const ContainerNode& scope, const Range& range)
 {
     return create(scope, EphemeralRange(&range));
 }
 
 }