Handle the situation where a `.dart` file generates a `.ng_meta.json`
file but does not register any reflective information.
An example of this would be a file that defines a const list that looks
like a directive alias. The transformer keeps track of this, and creates
a `.ng_meta.json` file but never creates a `.ng_deps.dart` file, which
can result in other files being linked to it and it not defining an
`initReflector` method.
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