Merge inbound to central, a=merge

MozReview-Commit-ID: DfRZi0gKjit

docshell/base/nsDocShell.cpp

@@ -5696,6 +5696,11 @@ nsDocShell::LoadPage(nsISupports* aPageDescriptor, uint32_t aDisplayType)
     }
     shEntry->SetURI(newUri);
     shEntry->SetOriginalURI(nullptr);
+    // shEntry's current triggering principal is whoever loaded that page initially.
+    // But now we're doing another load of the page, via an API that is only exposed
+    // to system code.  The triggering principal for this load should be the system
+    // principal.
+    shEntry->SetTriggeringPrincipal(nsContentUtils::GetSystemPrincipal());
   }
 
   rv = LoadHistoryEntry(shEntry, LOAD_HISTORY);