Introduce composed tree version of VisiblePosition

Source/core/editing/VisibleSelection.h

Index: Source/core/editing/VisibleSelection.h
diff --git a/Source/core/editing/VisibleSelection.h b/Source/core/editing/VisibleSelection.h
index 823a96220673f7d7fd00e1964244af005a0e8b20..5e897bbc386005aef1564465a8f14681c72cb2b6 100644
--- a/Source/core/editing/VisibleSelection.h
+++ b/Source/core/editing/VisibleSelection.h
@@ -97,11 +97,11 @@ public:
         static SelectionType selectionType(const VisibleSelection& selection) { return selection.selectionTypeInComposedTree(); }
         static VisiblePosition selectionVisibleStart(const VisibleSelection& selection)
         {
-            return createVisiblePosition(selectionStart(selection), isRange(selection) ? TextAffinity::Downstream : selection.affinity());
+            return createVisiblePositionInDOMTree(selectionStart(selection), isRange(selection) ? TextAffinity::Downstream : selection.affinity());
         }
         static VisiblePosition selectionVisibleEnd(const VisibleSelection& selection)
         {
-            return createVisiblePosition(selectionEnd(selection), isRange(selection) ? TextAffinity::Upstream : selection.affinity());
+            return createVisiblePositionInDOMTree(selectionEnd(selection), isRange(selection) ? TextAffinity::Upstream : selection.affinity());
         }
         static PositionType toPositionType(const Position& position) { return toPositionInComposedTree(position); }
     };