[4.0] Fix npm script on windows (#21505)

* Fix compile-es6 script on Windows machines.

* Adding back .min.js

Author: Thomas Hunziker

build/build-modules-js/compile-es6.js

@@ -27,7 +27,7 @@ const compileFile = (filePath) => {
     const fileName = filePath.slice(0, -7);
     console.log(`Compiling: ${fileName.replace('/build/media_src/', '/media/')}.js`);
     fs.writeFile(
-      `${fileName.replace('/build/media_src/', '/media/')}.js`,
+      `${fileName.replace('/build/media_src/', '/media/').replace('\\build\\media_src\\', '\\media\\')}.js`,
       result.code + os.EOL,
       (fsError) => {
         if (fsError) {
@@ -39,7 +39,7 @@ const compileFile = (filePath) => {
     );
     // Also write the minified
     fs.writeFile(
-      `${fileName.replace('/build/media_src/', '/media/')}.min.js`,
+      `${fileName.replace('/build/media_src/', '/media/').replace('\\build\\media_src\\', '\\media\\')}.min.js`,
       UglifyJS.minify(result.code).code + os.EOL,
       (fsError) => {
         if (fsError) {