js/libs/ember-1.5.1.js
function(className) {
    // lazily create elementClasses
    this.elementClasses = (this.elementClasses || new ClassSet());
    this.elementClasses.add(className);
    this.classes = this.elementClasses.list;

    return this;
  }
function(className) {
    // lazily create elementClasses
    this.elementClasses = (this.elementClasses || new ClassSet());
    this.elementClasses.add(className);
    this.classes = this.elementClasses.list;

    return this;
  }
Adds a class to the buffer, which will be rendered to the class attribute.

@method addClass
@param {String} className Class name to add to the buffer
@chainable