diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 5b96452a02f..ec4bdd43adb 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -587,10 +587,6 @@ class nsOuterWindowProxy : public js::Wrapper
 public:
   nsOuterWindowProxy() : js::Wrapper(0) { }
 
-  virtual bool isOuterWindow() {
-    return true;
-  }
-
   virtual bool finalizeInBackground(JS::Value priv) {
     return false;
   }
diff --git a/js/src/jsproxy.cpp b/js/src/jsproxy.cpp
index 847771c313b..db21b3a7737 100644
--- a/js/src/jsproxy.cpp
+++ b/js/src/jsproxy.cpp
@@ -3134,11 +3134,8 @@ ProxyObject::renew(JSContext *cx, BaseProxyHandler *handler, Value priv)
     JS_ASSERT_IF(IsCrossCompartmentWrapper(this), IsDeadProxyObject(this));
     JS_ASSERT(getParent() == cx->global());
     JS_ASSERT(getClass() == &uncallableClass_);
+    JS_ASSERT(!getClass()->ext.innerObject);
     JS_ASSERT(getTaggedProto().isLazy());
-#ifdef DEBUG
-    AutoSuppressGC suppressGC(cx);
-    JS_ASSERT(!handler->isOuterWindow());
-#endif
 
     setSlot(HANDLER_SLOT, PrivateValue(handler));
     setCrossCompartmentSlot(PRIVATE_SLOT, priv);
diff --git a/js/src/jsproxy.h b/js/src/jsproxy.h
index af74baceb79..5dd4072877f 100644
--- a/js/src/jsproxy.h
+++ b/js/src/jsproxy.h
@@ -122,10 +122,6 @@ class JS_FRIEND_API(BaseProxyHandler)
         return offsetof(BaseProxyHandler, mFamily);
     }
 
-    virtual bool isOuterWindow() {
-        return false;
-    }
-
     virtual bool finalizeInBackground(Value priv) {
         /*
          * Called on creation of a proxy to determine whether its finalize