CppTools: Remove QTC_ASSERT

A DiffEditorDocument has an empty file path.

Change-Id: If097497514afa82b1ed220a37cae410f4a81aa9a
Task-number: QTCREATORBUG-13489
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

src/plugins/cpptools/cppmodelmanager.cpp

@@ -693,8 +693,8 @@ void CppModelManager::updateVisibleEditorDocuments() const
     foreach (Core::IEditor *editor, Core::EditorManager::visibleEditors()) {
         if (const Core::IDocument *document = editor->document()) {
             const QString filePath = document->filePath();
-            QTC_ASSERT(!filePath.isEmpty(), continue);
-            visibleDocumentsInEditMode.insert(filePath);
+            if (!filePath.isEmpty())
+                visibleDocumentsInEditMode.insert(filePath);
         }
     }