Templatize PendingSelection class

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 ba6938d8f1e23483d44b3b9860007737aba27e52..45a4d61281c2dd28cfe8003893ee4d131b11df7e 100644
--- a/Source/core/editing/VisibleSelection.h
+++ b/Source/core/editing/VisibleSelection.h
@@ -43,6 +43,16 @@ class CORE_EXPORT VisibleSelection {
     DISALLOW_ALLOCATION();
     DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(VisibleSelection);
 public:
+    class InDOMTree {

[tkent, 2015/06/17 08:14:28]

The name |InDOMTree| sounds weird though I have no alternative idea.

+    public:
+        using PositionType = Position;
+
+        static PositionType selectionBase(const VisibleSelection& selection) { return selection.base(); }
+        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(); }
+    };
+
     VisibleSelection();
 
     VisibleSelection(const Position&, EAffinity, bool isDirectional = false);