qml: solve race condition when deleting while indexing

Task-number: QTCREATORBUG-10734

Change-Id: I521ac0881ff83a44846b133de5c292af8cda9d4e
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

src/plugins/qmljstools/qmljsmodelmanager.cpp

@@ -825,6 +825,8 @@ void ModelManager::parse(QFutureInterface<void> &future,
     QSet<QString> newLibraries;
 
     for (int i = 0; i < files.size(); ++i) {
+        if (future.isCanceled())
+            break;
         future.setProgressValue(qreal(i) / files.size() * progressRange);
 
         const QString fileName = files.at(i);