/* global document:false 
@memberOf tinto.html.properties
@this tinto.Component
@returns {Promise}
function label() {
  var self = this;

  return this.execute(function() {
    var id = this.getAttribute('id');
    var label = document.querySelector('label[for="' + id + '"]') || closestLabel(this);

    return label ? label.textContent.trim() : null;
  }).then(function(text) {
    if (text === null) {
      throw new Error(self.toString() + ' does not have a label');
    }

    return text;
  });
}