Implement <select> Popup Menu using PagePopup

Source/core/page/PagePopupClient.h

Index: Source/core/page/PagePopupClient.h
diff --git a/Source/core/page/PagePopupClient.h b/Source/core/page/PagePopupClient.h
index e67ec48da54441c8a473e3e173811aa436d4e81e..3ab7be1547753e5af9b97e320b6877ea196cfb29 100644
--- a/Source/core/page/PagePopupClient.h
+++ b/Source/core/page/PagePopupClient.h
@@ -38,6 +38,7 @@
 
 namespace blink {
 
+class Document;
 class Element;
 class Locale;
 
@@ -52,6 +53,9 @@ public:
     //  - window.setValueAndClosePopup(number, string).
     virtual void writeDocument(SharedBuffer*) = 0;
 
+    // This is called after the document is ready to do additionary setup.
+    virtual void didWriteDocument(Document&) = 0;
+
     virtual Element& ownerElement() = 0;
     // Returns a Locale object associated to the client.
     virtual Locale& locale() = 0;