libs/es6-shim.js
function(target, source) {
          if (!ES.TypeIsObject(target)) {
            throw new TypeError('target must be an object');
          }
          return Array.prototype.reduce.call(arguments, function(target, source) {
            if (!ES.TypeIsObject(source)) {
              throw new TypeError('source must be an object');
            }
            return Object.keys(source).reduce(function(target, key) {
              target[key] = source[key];
              return target;
            }, target);
          });
        }
function(target, source) {
          if (!ES.TypeIsObject(target)) {
            throw new TypeError('target must be an object');
          }
          return Array.prototype.reduce.call(arguments, function(target, source) {
            if (!ES.TypeIsObject(source)) {
              throw new TypeError('source must be an object');
            }
            return Object.keys(source).reduce(function(target, key) {
              target[key] = source[key];
              return target;
            }, target);
          });
        }
function ( target , source ) { if ( ! ES . TypeIsObject ( target ) ) { throw new TypeError ( 'target must be an object' ) ; } return Array . prototype . reduce . call ( arguments , function ( target , source ) { if ( ! ES . TypeIsObject ( source ) ) { throw new TypeError ( 'source must be an object' ) ; } return Object . keys ( source ) . reduce ( function ( target , key ) { target [ key ] = source [ key ] ; return target ; } , target ) ; } ) ; }
19.1.3.1
19 . 1 . 3 . 1