Popup open and hide using Alt+KeyDown

Source/web/PopupListBox.cpp

Index: Source/web/PopupListBox.cpp
diff --git a/Source/web/PopupListBox.cpp b/Source/web/PopupListBox.cpp
index 853ad3723cdb8b085fc424fe8776a5d801b78194..c79df0f785939bc001bf1721c6a039f9e9ced4b8 100644
--- a/Source/web/PopupListBox.cpp
+++ b/Source/web/PopupListBox.cpp
@@ -243,6 +243,11 @@ bool PopupListBox::handleKeyEvent(const PlatformKeyboardEvent& event)
         break;
     }
 
+    if (event.altKey() && (event.keyIdentifier() == "Down" || event.keyIdentifier() == "Up")) {
+        hidePopup();
+        return true;
+    }
+
     if (m_originalIndex != m_selectedIndex) {
         // Keyboard events should update the selection immediately (but we don't
         // want to fire the onchange event until the popup is closed, to match