title: Module not found: Error: Can't resolve 'classlist.js' in angular cli 6.1.3
body: <p>I am getting following while running <code>ng buid --watch</code> command in terminal,</p>
  
  <pre><code>ERROR in ./src/polyfills.ts
  Module not found: Error: Can't resolve 'classlist.js' in 'E:\eclipse_dis_workspace\tourdubai\UI\src'
  </code></pre>
  
  <p>following version used,</p>
  
  <pre><code>Angular CLI: 6.1.3
  Node: 8.11.3
  OS: win32 x64
  Angular: 6.1.2
  ... animations, common, compiler, compiler-cli, core, forms
  ... http, language-service, platform-browser
  ... platform-browser-dynamic, router
  
  Package                           Version
  -----------------------------------------------------------
  @angular-devkit/architect         0.7.3
  @angular-devkit/build-angular     0.7.5
  @angular-devkit/build-optimizer   0.7.5
  @angular-devkit/build-webpack     0.7.5
  @angular-devkit/core              0.7.3
  @angular-devkit/schematics        0.7.3
  @angular/cli                      6.1.3
  @ngtools/webpack                  6.1.5
  @schematics/angular               0.7.3
  @schematics/update                0.7.3
  rxjs                              6.2.2
  typescript                        2.7.2
  webpack                           4.9.2
  </code></pre>
  
  <p>i did all the setup configuration, like npm i. </p>
  
  <p>thanks in advance.</p>