title: React Select IE 11 - TypeError: Object doesn't support property or method 'assign'
body: <p>What is wrong with this code ...IE 11 throwing 
  TypeError: Object doesn't support property or method 'assign'...chrome is behaving fine</p>
  
  <pre><code>import React from 'react';
  
  import Select,{components} from 'react-select';
  import { colourOptions } from '../react-select_Samples/data.js';
  
  const Option = props =&gt; { 
      return ( &lt;div&gt;
          &lt;components.Option {...props}&gt;&lt;input type="checkbox" checked={props.isSelected} onChange={() =&gt; null} /&gt;{props.label}
          &lt;/components.Option&gt;&lt;/div&gt; ); 
      };
  export class SampleDropdown extends React.Component {
      render() {       
          return (
              &lt;Select
                className="basic-single"
                classNamePrefix="select"
                defaultValue={colourOptions[4]}
                isSearchable
                name="color"
                options={colourOptions}
                components={{ Option}}              
                hideSelectedOptions={false}
                isMulti
              /&gt;
          );
      }
  }
  </code></pre>
  
  <p>here is package.json  ...
  it has following packages
  "bootstrap(^3.4.1), es6-promise-promise(^1.0.0), react(^16.8.6), react-bootstrap(^0.31.5), react-dom(^16.8.6), react-router-bootstrap(^0.25.0), react-router-dom(^5.0.0), react-scripts(3.0.0), react-select(^2.4.3), rimraf(^2.6.3), whatwg-fetch(^3.0.0"</p>
  
  <pre><code>{
    "name": "reports_react",
    "version": "0.1.0",
    "private": true,
    "dependencies": {
      "bootstrap": "^3.4.1",
      "es6-promise-promise": "^1.0.0",
      "react": "^16.8.6",
      "react-bootstrap": "^0.31.5",
      "react-dom": "^16.8.6",
      "react-router-bootstrap": "^0.25.0",
      "react-router-dom": "^5.0.0",
      "react-scripts": "3.0.0",
      "react-select": "^2.4.3",
      "rimraf": "^2.6.3",
      "whatwg-fetch": "^3.0.0"
    },
    "scripts": {
      "start": "react-scripts start",
      "build": "react-scripts build",
      "test": "react-scripts test",
      "eject": "react-scripts eject"
    },
    "eslintConfig": {
      "extends": "react-app"
    },
    "browserslist": [
      "&gt;0.2%",
      "not dead",
      "not ie &lt;= 11",
      "not op_mini all"
    ]
  }
  
  </code></pre>