Make VisiblePosition constructor to canonicalize a position in composed tree

Source/core/dom/Position.h

Index: Source/core/dom/Position.h
diff --git a/Source/core/dom/Position.h b/Source/core/dom/Position.h
index cb4e4ad1a7173f4a335c3ebdcf8884fc48cd2547..c87e5a32e60c3614af4c24677d2d36de3fa2b5ab 100644
--- a/Source/core/dom/Position.h
+++ b/Source/core/dom/Position.h
@@ -453,6 +453,7 @@ typename Strategy::PositionType PositionAlgorithm<Strategy>::lastPositionInOrAft
 }
 
 PositionInComposedTree toPositionInComposedTree(const Position&);
+Position toPositionInDOMTree(const Position&);
 Position toPositionInDOMTree(const PositionInComposedTree&);
 
 } // namespace blink