MDL-67137 javascript: Add missing polyfills

.eslintignore

@@ -61,6 +61,7 @@ lib/amd/src/popper.js
 lib/geopattern-php/
 lib/php-jwt/
 lib/babel-polyfill/
+lib/mdn-polyfills/
 lib/emoji-data/
 lib/h5p/
 media/player/videojs/amd/src/video-lazy.js

.stylelintignore

@@ -62,6 +62,7 @@ lib/amd/src/popper.js
 lib/geopattern-php/
 lib/php-jwt/
 lib/babel-polyfill/
+lib/mdn-polyfills/
 lib/emoji-data/
 lib/h5p/
 media/player/videojs/amd/src/video-lazy.js

lib/mdn-polyfills/readme_moodle.txt

@@ -0,0 +1,13 @@
+The steps are essentially:
+1) Install mdn-polyfills package
+
+    npm install --no-save  mdn-polyfills
+
+2) Join them all together:
+
+    cd node_modules/mdn-polyfills
+    cat CustomEvent.* Element.* Function.* HTMLCanvasElement.* MouseEvent.* Node.prototype.* NodeList.* > ../../lib/mdn-polyfills/polyfill.js
+
+3) Uninstall the package again
+
+    npm uninstall --no-save mdn-polyfills

lib/outputrequirementslib.php

@@ -1608,6 +1608,9 @@ public function get_top_of_body_code(renderer_base $renderer) {
             $output .= html_writer::script('', $this->js_fix_url('/lib/babel-polyfill/polyfill.min.js'));
         }
 
+        // Include the MDN Polyfill.
+        $output .= html_writer::script('', $this->js_fix_url('/lib/mdn-polyfills/polyfill.js'));
+
         // YUI3 JS needs to be loaded early in the body. It should be cached well by the browser.
         $output .= $this->get_yui3lib_headcode();
 

lib/thirdpartylibs.xml

@@ -308,6 +308,12 @@
     <license>MIT</license>
     <version>6.26.0</version>
   </library>
+  <library>
+    <location>mdn-polyfills</location>
+    <name>mdn-polyfill</name>
+    <license>MIT</license>
+    <version>5.19.0</version>
+  </library>
   <library>
     <location>emoji-data</location>
     <name>Emoji data</name>