Implement <select> Popup Menu using PagePopup

Source/core/page/PagePopup.h

Index: Source/core/page/PagePopup.h
diff --git a/Source/core/page/PagePopup.h b/Source/core/page/PagePopup.h
index 5ade9e3072d3244d8ed3e11056dc889add027e48..348c046fb45b56252dbf2b1496dea26c25a53b87 100644
--- a/Source/core/page/PagePopup.h
+++ b/Source/core/page/PagePopup.h
@@ -31,6 +31,8 @@
 #ifndef PagePopup_h
 #define PagePopup_h
 
+#include "wtf/Forward.h"
+
 namespace blink {
 
 class AXObject;
@@ -40,6 +42,7 @@ class AXObject;
 class PagePopup {
 public:
     virtual AXObject* rootAXObject() = 0;
+    virtual void postMessage(const String& message) = 0;
 
 protected:
     virtual ~PagePopup() { }