QtMessageLogHandler: Fix crash

Set a parent when creating QtMessageLogItem.

Change-Id: I8faf76059dcc517794a4eb3d202bc14cd1632ca8
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>

src/plugins/debugger/qml/qmlengine.h

@@ -187,7 +187,8 @@ private:
 
     void updateEditor(Core::IEditor *editor, const QTextDocument *document);
     bool canEvaluateScript(const QString &script);
-    QtMessageLogItem *constructLogItemTree(const QVariant &result,
+    QtMessageLogItem *constructLogItemTree(QtMessageLogItem *parent,
+                                           const QVariant &result,
                                            const QString &key = QString());
     bool adjustBreakpointLineAndColumn(const QString &filePath, quint32 *line,
                                        quint32 *column, bool *valid);