QmlDesigner: Do not setup imports when checking

Change-Id: I4b3aabeb3384b25918ad9eac84fc44f1679da7a6
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/designercore/model/texttomodelmerger.cpp

@@ -1025,7 +1025,10 @@ bool TextToModelMerger::load(const QString &data, DifferenceHandler &differenceH
         collectLinkErrors(&errors, ctxt);
 
         setupImports(m_document, differenceHandler);
+
+        if (!justSanityCheck)
             setupPossibleImports(snapshot, m_vContext);
+
         qCInfo(rewriterBenchmark) << "imports setup:" << time.elapsed();
 
         collectImportErrors(&errors);