Previous implementation would fire changes `QueryList.changes.subscribe`
whenever the `QueryList` was recomputed. This resulted in artificially
high number of change notifications, as it is possible that recomputing
`QueryList` results in the same list. When the `QueryList` gets recomputed
is an implementation detail and it should not be the thing which determines
how often change event should fire.
This change introduces a new `emitDistinctChangesOnly` option for
`ContentChildren` and `ViewChildren`.
```
export class QueryCompWithStrictChangeEmitParent {
@ContentChildren('foo', {
// This option will become the default in the future
emitDistinctChangesOnly: true,
})
foos!: QueryList<any>;
}
```
PR Close#40091
e32b6256ce