no need for createBinding method

src/instance/bindings.js

@@ -13,7 +13,7 @@ var Observer = require('../observe/observer')
 
 exports._initBindings = function () {
   this._bindings = Object.create(null)
-  this._createBindingAt('$data')
+  this._bindings.$data = new Binding()
   // setup observer events
   this.$observer
     // simple updates
@@ -26,18 +26,6 @@ exports._initBindings = function () {
     .on('get', collectDep)
 }
 
-/**
- * Create a binding at a given path. Will also create
- * all bindings that do not exist yet along the way.
- *
- * @param {String} path
- * @return {Binding}
- */
-
-exports._createBindingAt = function (path) {
-  return this._bindings[path] = new Binding()
-}
-
 /**
  * Trigger update for the binding at given path.
  *

src/watcher.js

@@ -1,6 +1,7 @@
 var _ = require('./util')
 var Observer = require('./observe/observer')
 var expParser = require('./parse/expression')
+var Binding = require('./binding')
 var Batcher = require('./batcher')
 
 var batcher = new Batcher()
@@ -93,7 +94,7 @@ p.addDep = function (path) {
     if (!oldDeps[path]) {
       var binding =
         vm._bindings[path] ||
-        vm._createBindingAt(path)
+        (vm._bindings[path] = new Binding())
       binding._addSub(this)
     }
   }