Bug 1702405 - Add missing #include for MakeScopeExit. r=kmag

Differential Revision: https://phabricator.services.mozilla.com/D110517

dom/ipc/WindowGlobalChild.cpp

@@ -26,6 +26,7 @@
 #include "mozilla/dom/InProcessParent.h"
 #include "mozilla/ipc/Endpoint.h"
 #include "mozilla/PresShell.h"
+#include "mozilla/ScopeExit.h"
 #include "nsContentUtils.h"
 #include "nsDocShell.h"
 #include "nsFocusManager.h"