Bug 1562292: Part 1c - Set BrowsingContext Closed flag at the same time as outer window's. r=nika We rely on the Closed flag to avoid targeting named window open operations to windows which have already closed. The DocShell's lookup logic checks the Closed flag of the outer window, while BrowsingContext's checks the flag of the context. The latter, however, is only set when the window's DocShell is destroyed, which happens much later, and leaves closed windows returning true from IsTargetable() for much longer than they should. This patch immediately sets the BrowsingContext's closed flag at the same time as we set the same flag on the outer window, and leaves the existing setters in case of any corner cases. Differential Revision: https://phabricator.services.mozilla.com/D40494

--- a/dom/base/nsGlobalWindowOuter.cpp
+++ b/dom/base/nsGlobalWindowOuter.cpp
@@ -6327,16 +6327,18 @@ void nsGlobalWindowOuter::ForceClose() {
 
   FinalClose();
 }
 
 void nsGlobalWindowOuter::FinalClose() {
   // Flag that we were closed.
   mIsClosed = true;
 
+  GetBrowsingContext()->SetClosed(true);
+
   // If we get here from CloseOuter then it means that the parent process is
   // going to close our window for us. It's just important to set mIsClosed.
   if (XRE_GetProcessType() == GeckoProcessType_Content) {
     return;
   }
 
   // This stuff is non-sensical but incredibly fragile. The reasons for the
   // behavior here don't make sense today and may not have ever made sense,