Bug 1515590 part 4 - Don't call FixWaiverAfterTransplant if JS_TransplantObject didn't change object identity. r=bholley

Depends on D15093

Differential Revision: https://phabricator.services.mozilla.com/D15094

--HG--
extra : moz-landing-system : lando

js/xpconnect/wrappers/WrapperFactory.cpp

@@ -639,6 +639,11 @@ JSObject* TransplantObject(JSContext* cx, JS::HandleObject origobj,
     return newIdentity;
   }
 
+  // If we transplanted within a compartment, oldWaiver is still valid.
+  if (newIdentity == origobj) {
+    return newIdentity;
+  }
+
   if (!FixWaiverAfterTransplant(cx, oldWaiver, newIdentity)) {
     return nullptr;
   }