Fix leak when idx < 0

Change-Id: I51af14fb64acdc5f6904189d394be890e40e1a45
Reviewed-by: Nicolas Arnaud-Cormos <nicolas@kdab.com>
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

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

@@ -338,6 +338,8 @@ void RewriteActionCompressor::compressAddEditActions(QList<RewriteAction *> &act
         const int idx = actions.indexOf(action);
         if (newAction && idx >= 0)
             actions[idx] = newAction;
+        else
+            delete newAction;
     }
 }