Templatize FrameSelection::contains function

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 45a4d61281c2dd28cfe8003893ee4d131b11df7e..939fbc62a1263341a0ddede9710b0bbbe466ecc4 100644
--- a/Source/core/editing/VisibleSelection.h
+++ b/Source/core/editing/VisibleSelection.h
@@ -51,6 +51,9 @@ public:
         static PositionType selectionExtent(const VisibleSelection& selection) { return selection.extent(); }
         static PositionType selectionStart(const VisibleSelection& selection) { return selection.start(); }
         static PositionType selectionEnd(const VisibleSelection& selection) { return selection.end(); }
+        static VisiblePosition selectionVisibleStart(const VisibleSelection& selection) { return selection.visibleStart(); }
+        static VisiblePosition selectionVisibleEnd(const VisibleSelection& selection) { return selection.visibleEnd(); }
+        static PositionType toPositionType(const Position& position) { return position; }
     };
 
     VisibleSelection();