nomodule polyfill does not work when deferred

[kevinbuhmann]

🐞 Bug report

Command (mark with an x)

- [ ] new
- [x] build
- [ ] serve
- [ ] test
- [ ] e2e
- [ ] generate
- [ ] add
- [ ] update
- [ ] lint
- [ ] xi18n
- [ ] run
- [ ] config
- [ ] help
- [ ] version
- [ ] doc

Is this a regression?

Yes, the previous version in which this bug was not present was: 8.1.1

Description

I believe #15087 breaks the nomodule polyfill for older iOS/Safari. The nomodule polyfill script is now deferred by default and does not seem to work unless I remove the defer attribute.

🔥 Exception or Error

In the reproduction above, "Angular is running in the development mode. Call enableProdMode() to enable the production mode." is logged twice indicating that both the es5 and es2015 scripts were executed. You can prove this by added a console.log to main-es5.js and main-es2015.js.

In my internal application:

polyfills-es2015.d441479….js:1 Error: Zone.js has detected that ZoneAwarePromise `(window|global).Promise` has been overwritten.
Most likely cause is that a Promise polyfill has been loaded after Zone.js (Polyfilling Promise api is not necessary when zone.js is loaded. If you must load one, do so before loading zone.js.)

🔬 Minimal Reproduction

1. ng new ...
2. Add "iOS >=10" to browserslist to enable the nomodule polyfill.
3. ng build
4. Serve the output files using a static file server.
5. Open the site in iOS 10 (iPhone 7 Safari for example).
6. You can remove the defer attribute from the nomodule polyfill script in index.html manually and refresh to see the problem go away.

🌍 Your Environment

Angular CLI: 8.2.0
Node: 10.15.3
OS: win32 x64
Angular: 8.2.0
... animations, cli, common, compiler, compiler-cli, core
... elements, forms, language-service, platform-browser
... platform-browser-dynamic, platform-server, router

Package                                    Version
--------------------------------------------------------------------
@angular-devkit/architect                  0.802.0
@angular-devkit/build-angular              0.802.0
@angular-devkit/build-optimizer            0.802.0
@angular-devkit/core                       8.2.0
@angular-devkit/schematics                 8.2.0
@nguniversal/common                        8.1.1
@nguniversal/module-map-ngfactory-loader   8.1.1
@schematics/angular                        8.0.0
@schematics/update                         0.802.0
rxjs                                       6.5.2
typescript                                 3.5.3
webpack                                    4.29.5

Anything else relevant?
This happens on iOS 10.3 and probably older.

[clydin]

Fixed via #15246 which has just been merged.

[kevinbuhmann]

Thanks!

[clydin]

An 8.2 patch version of the fix is also pending: #15276

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}