GUI -- TopoView - don't add source port on host link.

Change-Id: Ia1a298eb6cab9da1c209c8365b244025468f1a20

@@ -198,21 +198,24 @@
         d.el.classed('enhanced', true);
         d.el.classed('enhanced', true);
         $log.debug('[' + (d.srcPort || 'H') + '] ---> [' + d.tgtPort + ']', d.key);
         $log.debug('[' + (d.srcPort || 'H') + '] ---> [' + d.tgtPort + ']', d.key);
 
 
-        // define port label data objects
-        var data = [
-            {
-                id: 'topo-port-src',
-                num: d.srcPort,
-                baseX: d.source.x,
-                baseY: d.source.y
-            },
-            {
+        // Define port label data objects.
+        // NOTE: src port is absent in the case of host-links.
+
+        var data = [{
             id: 'topo-port-tgt',
             id: 'topo-port-tgt',
             num: d.tgtPort,
             num: d.tgtPort,
             baseX: d.target.x,
             baseX: d.target.x,
             baseY: d.target.y
             baseY: d.target.y
+        }];
+
+        if (d.srcPort) {
+            data.push({
+                id: 'topo-port-src',
+                num: d.srcPort,
+                baseX: d.source.x,
+                baseY: d.source.y
+            });
         }
         }
-        ];
 
 
         td3.applyPortLabels(data, api.portLabelG());
         td3.applyPortLabels(data, api.portLabelG());
     }
     }