removed duplicated watcher on filter

src/components/TreeRoot.vue

@@ -113,6 +113,7 @@
         default: 'div'
       }
     },
+
     data () {
       // we should not mutating a prop directly...
       // that's why we have to create a new object
@@ -134,30 +135,25 @@
         draggableNode: null
       }
     },
+
     computed: {
       visibleModel() {
         return this.model.filter(function(node) {
           return node && node.visible()
         }) 
       },
-
       visibleMatches() {
         return this.matches.filter(function(node) {
           return node && node.visible()
         })
       }
     },
+    
     watch: {
       filter (term) {
         this.tree.filter(term)
       }
     },
-
-    watch: {
-      filter (term) {
-        this.tree.filter(term)
-      }
-    }
   }
 </script>