Use tighter typing in editing: DeleteSelectionCommand

Source/core/editing/DeleteSelectionCommand.h

Index: Source/core/editing/DeleteSelectionCommand.h
diff --git a/Source/core/editing/DeleteSelectionCommand.h b/Source/core/editing/DeleteSelectionCommand.h
index 6ebcb4f25a99f6f27640ced6b9c45e4781730800..44d2f966f157f9752a40c0684560998ae8dc24e1 100644
--- a/Source/core/editing/DeleteSelectionCommand.h
+++ b/Source/core/editing/DeleteSelectionCommand.h
@@ -31,6 +31,7 @@
 namespace blink {
 
 class EditingStyle;
+class HTMLTableRowElement;
 
 class DeleteSelectionCommand FINAL : public CompositeEditCommand {
 public:
@@ -92,10 +93,10 @@ private:
     RefPtrWillBeMember<Node> m_endBlock;
     RefPtrWillBeMember<EditingStyle> m_typingStyle;
     RefPtrWillBeMember<EditingStyle> m_deleteIntoBlockquoteStyle;
-    RefPtrWillBeMember<Node> m_startRoot;
-    RefPtrWillBeMember<Node> m_endRoot;
-    RefPtrWillBeMember<Node> m_startTableRow;
-    RefPtrWillBeMember<Node> m_endTableRow;
+    RefPtrWillBeMember<Element> m_startRoot;
+    RefPtrWillBeMember<Element> m_endRoot;
+    RefPtrWillBeMember<HTMLTableRowElement> m_startTableRow;
+    RefPtrWillBeMember<HTMLTableRowElement> m_endTableRow;
     RefPtrWillBeMember<Node> m_temporaryPlaceholder;
 };