Lambda not supported for AOT

[Sjerd]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[X] Bug report  
[ ] Performance issue
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question
[ ] Other... Please describe:

Current behavior

Write a custom validator per docs: https://angular.io/guide/form-validation and try to build with --prod flag for AOT compiler

Expected behavior

Be able to built with AOT without build error:

BUILD ERROR
: Error: /home/test/src/validators/generic.validator.ts:17:1: Error encountered in metadata generated for exported symbol 'GenericValidator':
/home/test/src/validators/generic.validator.ts:40:12: Metadata collected contains an error that will be reported at runtime: Lambda not supported.
 {"__symbolic":"error","message":"Lambda not supported","line":39,"character":11}

Minimal reproduction of the problem with instructions

Download:
https://stackblitz.com/edit/angular-gitter-tsgzld
And built with npm i && ng build --prod

What is the motivation / use case for changing the behavior?

Following the instructions from the official docs triggers a build error.
https://angular.io/guide/aot-compiler
https://angular.io/guide/form-validation

Environment

Angular version: 5.2.11

 
For Tooling issues:
- Node version: v10.10.0
- Platform:  Linux

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