Method setAttribute

src/core/a-node.js:265–268

(attr, newValue)

  }

  setAttribute (attr, newValue) {
    if (attr === 'mixin') { this.updateMixins(newValue); }
    window.HTMLElement.prototype.setAttribute.call(this, attr, newValue);
  }

  /**
   * Removes the mixin element from `mixinEls`.