fix(@angular-devkit/build-angular): load polyfills-es5 on test

Fix #14335

Author: filipesilva

packages/angular_devkit/build_angular/src/angular-cli-files/plugins/karma-context.html

@@ -29,6 +29,7 @@
   </script>
   <script src="_karma_webpack_/runtime.js" crossorigin="anonymous"></script>
   <script src="_karma_webpack_/polyfills.js" crossorigin="anonymous"></script>
+  <script src="_karma_webpack_/polyfills-es5.js" crossorigin="anonymous" nomodule></script>
   <!-- Dynamically replaced with <script> tags -->
   %SCRIPTS%
   <script src="_karma_webpack_/styles.js" crossorigin="anonymous"></script>

packages/angular_devkit/build_angular/src/angular-cli-files/plugins/karma-debug.html

@@ -30,6 +30,7 @@
   </script>
   <script src="_karma_webpack_/runtime.js" crossorigin="anonymous"></script>
   <script src="_karma_webpack_/polyfills.js" crossorigin="anonymous"></script>
+  <script src="_karma_webpack_/polyfills-es5.js" crossorigin="anonymous" nomodule></script>
   <!-- Dynamically replaced with <script> tags -->
   %SCRIPTS%
   <script src="_karma_webpack_/styles.js" crossorigin="anonymous"></script>

packages/angular_devkit/build_angular/src/angular-cli-files/plugins/karma.ts

@@ -209,6 +209,7 @@ const init: any = (config: any, emitter: any, customFileHandlers: any) => {
         const alwaysServe = [
           '/_karma_webpack_/runtime.js',
           '/_karma_webpack_/polyfills.js',
+          '/_karma_webpack_/polyfills-es5.js',
           '/_karma_webpack_/scripts.js',
           '/_karma_webpack_/styles.js',
           '/_karma_webpack_/vendor.js',