old_contents: class Polyfill {
  
      static install() {
          // ES6 Object.setPrototypeOf
          Object.setPrototypeOf = Object.setPrototypeOf || function (obj, proto) {
              obj.__proto__ = proto;
              return obj;
          };
  
          // ES6 Object.assign
          Object.assign = Object.assign || function (target) {
              if (target === undefined || target === null) {
                  throw new TypeError('Cannot convert undefined or null to object');
              }
  
              let output = Object(target);
              for (let i = 1; i < arguments.length; i++) {
                  let source = arguments[i];
                  if (source !== undefined && source !== null) {
                      for (let key in source) {
                          if (source.hasOwnProperty(key)) {
                              output[key] = source[key];
                          }
                      }
                  }
              }
              return output;
          };
  
          // ES6 Promise (missing support in IE11)
          if (typeof self.Promise !== 'function') {
              require('es6-promise').polyfill();
          }
      }
  
  }
  
  Polyfill.install();
  
  export default Polyfill;
new_contents: class Polyfill {
  
      static install() {
          // ES6 Object.setPrototypeOf
          Object.setPrototypeOf = Object.setPrototypeOf || function (obj, proto) {
              obj.__proto__ = proto;
              return obj;
          };
  
          // ES6 Object.assign
          Object.assign = Object.assign || function (target) {
              if (target === undefined || target === null) {
                  throw new TypeError('Cannot convert undefined or null to object');
              }
  
              let output = Object(target);
              for (let i = 1; i < arguments.length; i++) {
                  let source = arguments[i];
                  if (source !== undefined && source !== null) {
                      for (let key in source) {
                          if (source.hasOwnProperty(key)) {
                              output[key] = source[key];
                          }
                      }
                  }
              }
              return output;
          };
  
          // ES6 Promise (missing support in IE11)
          if (typeof self.Promise !== 'function') {
              // polyfill() will be called internally during module load
              require('es6-promise');
          }
      }
  
  }
  
  Polyfill.install();
  
  export default Polyfill;
subject: Adjust es6-promise polyfill call