Use the showContextMenuOnMouseUp setting instead of #ifdef.

Source/core/page/EventHandler.cpp

Index: Source/core/page/EventHandler.cpp
diff --git a/Source/core/page/EventHandler.cpp b/Source/core/page/EventHandler.cpp
index 7624a0e919aee46f771d5949e1c03a6043fa0701..2b1198990eb28690643830deddd25a10a0a29bee 100644
--- a/Source/core/page/EventHandler.cpp
+++ b/Source/core/page/EventHandler.cpp
@@ -2813,12 +2813,9 @@ bool EventHandler::sendContextMenuEventForKey()
 
     // The contextmenu event is a mouse event even when invoked using the keyboard.
     // This is required for web compatibility.
-
-#if OS(WIN)
-    PlatformEvent::Type eventType = PlatformEvent::MouseReleased;
-#else
     PlatformEvent::Type eventType = PlatformEvent::MousePressed;
-#endif
+    if (m_frame->settings()->showContextMenuOnMouseUp())
+        eventType = PlatformEvent::MouseReleased;
 
     PlatformMouseEvent mouseEvent(position, globalPosition, RightButton, eventType, 1, false, false, false, false, PlatformMouseEvent::RealOrIndistinguishable, WTF::currentTime());