Backed out 2 changesets (bug 1810619) for causing wd failures in dom_content_loaded.py CLOSED TREE

Backed out changeset 81d6ef111d4f (bug 1810619)
Backed out changeset 637be53c4d27 (bug 1810619)

docshell/base/nsDocShell.h

@@ -558,6 +558,11 @@ class nsDocShell final : public nsDocLoader,
   nsDocShell(mozilla::dom::BrowsingContext* aBrowsingContext,
              uint64_t aContentWindowID);
 
+  // Security check to prevent frameset spoofing. See comments at
+  // implementation site.
+  static bool ValidateOrigin(mozilla::dom::BrowsingContext* aOrigin,
+                             mozilla::dom::BrowsingContext* aTarget);
+
   static inline uint32_t PRTimeToSeconds(PRTime aTimeUsec) {
     return uint32_t(aTimeUsec / PR_USEC_PER_SEC);
   }