Bug 1217047 - try harder in IsContractIDRegistered to return a reasonable answer; r=bsmedberg,f=yury

xpcom/components/nsComponentManager.cpp

@@ -1749,7 +1749,12 @@ nsComponentManagerImpl::IsContractIDRegistered(const char* aClass,
   nsFactoryEntry* entry = GetFactoryEntry(aClass, strlen(aClass));
 
   if (entry) {
-    *aResult = true;
+    // UnregisterFactory might have left a stale nsFactoryEntry in
+    // mContractIDs, so we should check to see whether this entry has
+    // anything useful.
+    *aResult = (bool(entry->mModule) ||
+                bool(entry->mFactory) ||
+                bool(entry->mServiceObject));
   } else {
     *aResult = false;
   }