fix(docs-infra): fix angular.io on IE 11 (#41162)

Previously, the angular.io app was broken on IE 11. In particular, pages
that included Custom Elements would fail to load, because the
`Reflect.construct()` method (which the Custom Elements ES5 shim relies
on) was not available.

This commit fixes this by loading the polyfill for `Reflect.construct()`
on browsers that do not support ES2015 (including IE 11).

PR Close #41162

aio/angular.json

@@ -49,6 +49,11 @@
                 "glob": "native-shim.js",
                 "input": "node_modules/@webcomponents/custom-elements/src",
                 "output": "/assets/js"
+              },
+              {
+                "glob": "es.reflect.construct.js",
+                "input": "node_modules/core-js/modules",
+                "output": "/assets/js"
               }
             ],
             "styles": [
@@ -156,6 +161,11 @@
                 "glob": "native-shim.js",
                 "input": "node_modules/@webcomponents/custom-elements/src",
                 "output": "/assets/js"
+              },
+              {
+                "glob": "es.reflect.construct.js",
+                "input": "node_modules/core-js/modules",
+                "output": "/assets/js"
               }
             ],
             "styles": [

aio/ngsw-config.json

@@ -13,6 +13,7 @@
           "/assets/js/*.js",
           "/*.css",
           "/*.js",
+          "!/assets/js/es.reflect.construct.js",
           "!/assets/js/native-shim.js",
           "!/*-es5*.js"
         ],
@@ -40,6 +41,7 @@
       "resources": {
         "files": [
           "/assets/images/favicons/**",
+          "/assets/js/es.reflect.construct.js",
           "/assets/js/native-shim.js",
           "/*-es5*.js",
           "!/**/_unused/**"

aio/src/index.html

@@ -118,6 +118,7 @@
           - Samsung browser 5.0-8.1 (~0.43% global usage)
           - Opera 41-47 (~0.02% global usage)
   -->
+  <script src="assets/js/es.reflect.construct.js" nomodule></script>;
   <script src="assets/js/native-shim.js" nomodule></script>;
 
 </body>