Libraries that create components dynamically using component factories,
such as `@angular/upgrade` need to pass blocks of projected content
through to the `ComponentFactory.create()` method. These blocks
are extracted from the content by matching CSS selectors defined in
`<ng-content select="..">` tags found in the component's template.
The Angular compiler collects these CSS selectors when compiling a component's
template, and exposes them via the `ComponentFactory.ngContentSelectors`
property.
This change ensures that this property is filled correctly when the
component factory is created by compiling a component with the Ivy engine.
PR Close#27867
feebe03523