Get rid of a redundant function Position::deprecatedEditingOffset()

Source/core/editing/iterators/SimplifiedBackwardsTextIterator.cpp

Index: Source/core/editing/iterators/SimplifiedBackwardsTextIterator.cpp
diff --git a/Source/core/editing/iterators/SimplifiedBackwardsTextIterator.cpp b/Source/core/editing/iterators/SimplifiedBackwardsTextIterator.cpp
index 63ff7bb8bfc015bf9b2f9b1050bddd2ed144b1aa..c81848ecfa5bb4ce4e9a7b6f23b92462a41f8aff 100644
--- a/Source/core/editing/iterators/SimplifiedBackwardsTextIterator.cpp
+++ b/Source/core/editing/iterators/SimplifiedBackwardsTextIterator.cpp
@@ -86,8 +86,8 @@ SimplifiedBackwardsTextIteratorAlgorithm<Strategy>::SimplifiedBackwardsTextItera
     if (!startNode)
         return;
     Node* endNode = end.anchorNode();
-    int startOffset = start.deprecatedEditingOffset();
-    int endOffset = end.deprecatedEditingOffset();
+    int startOffset = start.computeEditingOffset();
+    int endOffset = end.computeEditingOffset();
 
     init(startNode, endNode, startOffset, endOffset);
 }