Add focus action support to NightmareJS.

nightmare-action-focus.js

var Nightmare = require( 'nightmare' );

/**
 * Add focus action to NightmareJS
 *
 * Usage:
 * .focus( selector ) => .focus( '.myClass' )
 */
Nightmare.action( 'focus', function ( selector, done ) {
  this.evaluate_now(( selector ) => {
    document.activeElement.blur();
    var element = document.querySelector( selector );
    element.focus();
  }, done, selector );
});