Currently developers can use the `By` class to construct common
`DebugElement` query predicates. e.g. `By.directive(MyDirective)`.
The `directive()` and `all()` predicates are currently returning
a predicate that works for `DebugElement` nodes. This return type
is too strict since the predicate is not specific to `DebugElement`
instances and can also apply to `DebugNode` instances.
Meaning that developers are currently able to use the `directive()`
predicate when using `queryAllNodes()`. This is a common practice
but will break when the project is compiled with TypeScript's
`--strictFunctionTypes` flag as the `DebugElement` predicate type
is not assignable to predicates for `DebugNode`. In order to make
these predicates usable with `--strictFuntionTypes` enabled, we
adjust the predicate type to reflect what is actually needed for
evaluation of the predicate.
PR Close#30993
10a1e1974b