Use union types for HTMLSelectElement.add()'s arguments

Source/core/html/HTMLSelectElement.h

Index: Source/core/html/HTMLSelectElement.h
diff --git a/Source/core/html/HTMLSelectElement.h b/Source/core/html/HTMLSelectElement.h
index 988f9281aca0322fbe033660d51a3a40961c35f7..9e350d15acfcca1936a54b93fc630a99c167596c 100644
--- a/Source/core/html/HTMLSelectElement.h
+++ b/Source/core/html/HTMLSelectElement.h
@@ -37,6 +37,8 @@ namespace blink {
 class AutoscrollController;
 class ExceptionState;
 class HTMLOptionElement;
+class HTMLOptionElementOrHTMLOptGroupElement;
+class HTMLElementOrLong;
 
 class HTMLSelectElement final : public HTMLFormControlElementWithState, public TypeAheadDataSource {
     DEFINE_WRAPPERTYPEINFO();
@@ -64,8 +66,7 @@ public:
 
     bool usesMenuList() const;
 
-    void add(HTMLElement*, HTMLElement* beforeElement, ExceptionState&);
-    void addBeforeOptionAtIndex(HTMLElement*, int beforeIndex, ExceptionState&);
+    void add(const HTMLOptionElementOrHTMLOptGroupElement&, const HTMLElementOrLong&, ExceptionState&);
 
     using Node::remove;
     void remove(int index);