bug 804220 - Make IDBWrapperCache::SetScriptOwner infallible. r=khuey

dom/indexedDB/IDBDatabase.cpp

@@ -188,10 +188,7 @@ IDBDatabase::Create(IDBWrapperCache* aOwnerCache,
   nsRefPtr<IDBDatabase> db(new IDBDatabase());
 
   db->BindToOwner(aOwnerCache);
-  if (!db->SetScriptOwner(aOwnerCache->GetScriptOwner())) {
-    return nullptr;
-  }
-
+  db->SetScriptOwner(aOwnerCache->GetScriptOwner());
   db->mFactory = aFactory;
   db->mDatabaseId = databaseInfo->id;
   db->mName = databaseInfo->name;

dom/indexedDB/IDBRequest.cpp

@@ -57,10 +57,7 @@ IDBRequest::Create(nsISupports* aSource,
   request->mSource = aSource;
   request->mTransaction = aTransaction;
   request->BindToOwner(aOwnerCache);
-  if (!request->SetScriptOwner(aOwnerCache->GetScriptOwner())) {
-    return nullptr;
-  }
-
+  request->SetScriptOwner(aOwnerCache->GetScriptOwner());
   request->CaptureCaller(aCallingCx);
 
   return request.forget();
@@ -352,10 +349,7 @@ IDBOpenDBRequest::Create(IDBFactory* aFactory,
   nsRefPtr<IDBOpenDBRequest> request = new IDBOpenDBRequest();
 
   request->BindToOwner(aOwner);
-  if (!request->SetScriptOwner(aScriptOwner)) {
-    return nullptr;
-  }
-
+  request->SetScriptOwner(aScriptOwner);
   request->CaptureCaller(aCallingCx);
   request->mFactory = aFactory;
 

dom/indexedDB/IDBTransaction.cpp

@@ -103,10 +103,7 @@ IDBTransaction::CreateInternal(IDBDatabase* aDatabase,
   nsRefPtr<IDBTransaction> transaction = new IDBTransaction();
 
   transaction->BindToOwner(aDatabase);
-  if (!transaction->SetScriptOwner(aDatabase->GetScriptOwner())) {
-    return nullptr;
-  }
-
+  transaction->SetScriptOwner(aDatabase->GetScriptOwner());
   transaction->mDatabase = aDatabase;
   transaction->mMode = aMode;
   transaction->mDatabaseInfo = aDatabase->Info();

dom/indexedDB/IDBWrapperCache.cpp

@@ -45,7 +45,7 @@ IDBWrapperCache::~IDBWrapperCache()
   NS_DROP_JS_OBJECTS(this, IDBWrapperCache);
 }
 
-bool
+void
 IDBWrapperCache::SetScriptOwner(JSObject* aScriptOwner)
 {
   NS_ASSERTION(aScriptOwner, "This should never be null!");
@@ -56,8 +56,6 @@ IDBWrapperCache::SetScriptOwner(JSObject* aScriptOwner)
   nsXPCOMCycleCollectionParticipant* participant;
   CallQueryInterface(this, &participant);
   nsContentUtils::HoldJSObjects(thisSupports, participant);
-
-  return true;
 }
 
 #ifdef DEBUG

dom/indexedDB/IDBWrapperCache.h

@@ -25,7 +25,7 @@ public:
   {
     return mScriptOwner;
   }
-  bool SetScriptOwner(JSObject* aScriptOwner);
+  void SetScriptOwner(JSObject* aScriptOwner);
 
   JSObject* GetParentObject()
   {