Use tighter typing in editing/

Source/core/editing/WrapContentsInDummySpanCommand.h

Index: Source/core/editing/WrapContentsInDummySpanCommand.h
diff --git a/Source/core/editing/WrapContentsInDummySpanCommand.h b/Source/core/editing/WrapContentsInDummySpanCommand.h
index 2b8356457c7b53f8c4e9d0b9e07e1050540700a2..2c101a7ff6361b85d5850a198096f795fcd3d174 100644
--- a/Source/core/editing/WrapContentsInDummySpanCommand.h
+++ b/Source/core/editing/WrapContentsInDummySpanCommand.h
@@ -30,7 +30,7 @@
 
 namespace blink {
 
-class HTMLElement;
+class HTMLSpanElement;
 
 class WrapContentsInDummySpanCommand FINAL : public SimpleEditCommand {
 public:
@@ -50,7 +50,7 @@ private:
     void executeApply();
 
     RefPtrWillBeMember<Element> m_element;
-    RefPtrWillBeMember<HTMLElement> m_dummySpan;
+    RefPtrWillBeMember<HTMLSpanElement> m_dummySpan;
 };
 
 } // namespace blink