Remove legacy SELECT popup code.

Source/platform/HostWindow.h

Index: Source/platform/HostWindow.h
diff --git a/Source/platform/HostWindow.h b/Source/platform/HostWindow.h
index 1045fc9edbe9a9a5d4869734a1099eb7ed6b767f..2be101995b12aff51235142fcfaaedabd084b30d 100644
--- a/Source/platform/HostWindow.h
+++ b/Source/platform/HostWindow.h
@@ -27,7 +27,6 @@
 #define HostWindow_h
 
 #include "platform/PlatformExport.h"
-#include "platform/graphics/paint/DisplayItemClient.h"
 #include "wtf/FastAllocBase.h"
 #include "wtf/Noncopyable.h"
 
@@ -44,12 +43,6 @@ public:
     // Requests the host invalidate the contents.
     virtual void invalidateRect(const IntRect& updateRect) = 0;
 
-    // Requests the host to invalidate display items, if owned by the host
-    // window. At present Chrome does not (display items are owned by the
-    // GraphicsLayer instead), but PopupContainerClient does.
-    virtual void invalidateDisplayItemClient(DisplayItemClient) { }
-    virtual void invalidateAllDisplayItems() { }
-
     // Converts from the window coordinates to screen coordinates.
     virtual IntRect viewportToScreen(const IntRect&) const = 0;