Introduce visiblePositionOf() for Position and PositionInComposedTree

Source/core/editing/FrameSelection.cpp

Index: Source/core/editing/FrameSelection.cpp
diff --git a/Source/core/editing/FrameSelection.cpp b/Source/core/editing/FrameSelection.cpp
index f297f0ab1d22aba44aa86ee7f9fe32dbf2933e04..7ec1edf67b601b83597f1cda6c78d0a412076d1c 100644
--- a/Source/core/editing/FrameSelection.cpp
+++ b/Source/core/editing/FrameSelection.cpp
@@ -202,9 +202,9 @@ void FrameSelection::setNonDirectionalSelectionIfNeededAlgorithm(const VisibleSe
     VisibleSelection newSelection = passedNewSelection;
     bool isDirectional = shouldAlwaysUseDirectionalSelection(m_frame) || newSelection.isDirectional();
 
-    VisiblePosition base = m_originalBase.isNotNull() ? m_originalBase : VisiblePosition(Strategy::selectionBase(newSelection));
+    VisiblePosition base = m_originalBase.isNotNull() ? m_originalBase : visiblePositionOf(Strategy::selectionBase(newSelection));
     VisiblePosition newBase = base;
-    VisiblePosition extent(Strategy::selectionExtent(newSelection));
+    VisiblePosition extent = visiblePositionOf(Strategy::selectionExtent(newSelection));
     VisiblePosition newExtent = extent;
     if (endpointsAdjustmentMode == AdjustEndpointsAtBidiBoundary)
         adjustEndpointsAtBidiBoundary(newBase, newExtent);