Move LayoutObject::previousOffsetForBackwardDeletion() to editing.

third_party/WebKit/Source/core/layout/LayoutText.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 1632 matching lines @@
 }
 
 unsigned LayoutText::resolvedTextLength() const
 {
     int len = 0;
     for (InlineTextBox* box = firstTextBox(); box; box = box->nextTextBox())
         len += box->len();
     return len;
 }
 
-int LayoutText::previousOffsetForBackwardDeletion(int current) const
-{
-    // Delete by one code point. Ideally we should delete grapheme where that
-    // makes sense. https://crbug.com/587241
-    if (U16_IS_TRAIL(m_text[--current]))
-        --current;
-    if (current < 0)
-        current = 0;
-    return current;
-}
-
 bool LayoutText::computeCanUseSimpleFontCodePath() const
 {
     if (m_text.is8Bit())
         return true;
     return Character::characterRangeCodePath(characters16(), length()) == SimplePath;
 }
 
 #if ENABLE(ASSERT)
 
 void LayoutText::checkConsistency() const
@@ skipping 36 matching lines @@
     for (InlineTextBox* box = firstTextBox(); box; box = box->nextTextBox()) {
         paintInvalidationContainer.invalidateDisplayItemClientOnBacking(*box, invalidationReason);
         if (box->truncation() != cNoTruncation) {
             if (EllipsisBox* ellipsisBox = box->root().ellipsisBox())
                 paintInvalidationContainer.invalidateDisplayItemClientOnBacking(*ellipsisBox, invalidationReason);
         }
     }
 }
 
 } // namespace blink