fix new error in implicit velocity output

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@10735 2fb0f335-1f38-0410-981e-8018bf24f1b0

dumux/implicit/common/implicitvelocityoutput.hh

@@ -88,7 +88,7 @@ public:
                 velocityOutput_ = false;
             }
 
-            if (isBox)
+            if (velocityOutput_ && isBox)
             {
                 FVElementGeometry fvGeometry;
                 fvGeometry.update(problem_.gridView(), *elemIt);