I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[ ] Performance issue
[X] 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

On implementing an optional custom strategy provider, when I create a new custom element with an angular component, I am forced to implement a complete new custom strategy provider with an own factory.

Expected behavior

But if I want to hook up a custom behavior to the default ComponentNgElementStrategy, I have to copy&paste the default class. Maybe it would be better, to import the default class that the custom element strategy could inherit from the default one.

Minimal reproduction of the problem with instructions

I have pushed an angular elements example with a custom behavior hooked up into the default copied and pasted ComponentNgElementStrategy on the connect method:
https://github.com/jKelio/angular-element-example

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

Avoiding too much coping&pasting stuff from the angular framework itself.

Environment

Angular version: 6.1.0