Templatize FrameSelection::setNonDirectionalSelectionIfNeede function

Source/core/editing/VisibleSelection.cpp

Index: Source/core/editing/VisibleSelection.cpp
diff --git a/Source/core/editing/VisibleSelection.cpp b/Source/core/editing/VisibleSelection.cpp
index f5b17d66247d40c25922ae0b93964a881d436c27..1026a939b56a50609928566ddc1bfea3f32a5692 100644
--- a/Source/core/editing/VisibleSelection.cpp
+++ b/Source/core/editing/VisibleSelection.cpp
@@ -871,6 +871,11 @@ void VisibleSelection::validatePositionsIfNeeded()
         validate();
 }
 
+bool VisibleSelection::InDOMTree::equalSelections(const VisibleSelection& selection1, const VisibleSelection& selection2)
+{
+    return selection1 == selection2;
+}
+
 #ifndef NDEBUG
 
 void VisibleSelection::debugPosition() const