QmlDesigner: Fix crash for in file component change

Change-Id: I666dd0ca2b7e50584ae2ad5577ec2f4c685fb209
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

src/plugins/qmldesigner/components/integration/designdocument.cpp

@@ -153,8 +153,6 @@ bool DesignDocument::loadInFileComponent(const ModelNode &componentNode)
 
     if (!componentNode.isRootNode()) {
         //change to subcomponent model
-        if (m_inFileComponentTextModifier)
-            delete m_inFileComponentTextModifier.data();
 
         m_inFileComponentTextModifier.reset(createComponentTextModifier(m_documentTextModifier.data(), rewriterView(), componentText, componentNode));