Bug 1275190 - Assert that the SavedFrame* pointers we get out of js::SavedStacks::frames are not null; r=jimb

CLOSED TREE to kick off new builds

--HG--
extra : amend_source : ff0a27a79552e0245b46d26c26f5eea65c4d5a3e
extra : histedit_source : 980d1edd960abb08acbf83965ac647e156c64678

js/src/vm/SavedStacks.cpp

@@ -1361,8 +1361,10 @@ SavedStacks::getOrCreateSavedFrame(JSContext* cx, SavedFrame::HandleLookup looku
 {
     const SavedFrame::Lookup& lookupInstance = lookup.get();
     DependentAddPtr<SavedFrame::Set> p(cx, frames, lookupInstance);
-    if (p)
+    if (p) {
+        MOZ_ASSERT(*p);
         return *p;
+    }
 
     RootedSavedFrame frame(cx, createFrameFromLookup(cx, lookup));
     if (!frame)