js/libs/ember-1.5.1.js
function(key) {
        var dict = this.dict;

        if (dict.hasOwnProperty(key)) {
          return true;
        }

        if (this.parent) {
          return this.parent.has(key);
        }

        return false;
      }
function(key) {
        var dict = this.dict;

        if (dict.hasOwnProperty(key)) {
          return true;
        }

        if (this.parent) {
          return this.parent.has(key);
        }

        return false;
      }
Check for the existence of given a key, if the key is present at the current
level return true, otherwise walk up the parent hierarchy and try again. If
no matching key is found, return false.

@method has
@param {String} key
@return {Boolean}