Sometimes UMD exports appear in the following form:
```
exports.MyClass = alias1 = alias2 = <<declaration>>
```
Previously the declaration of the export would have been captured
as `alias1 = alias2 = <<declaration>>`, which the `PartialInterpreter`
would have failed on, since it cannot handle assignments.
Now we skip over these aliases capturing only the `<<declaration>>`
expression.
Fixes#38947
PR Close#38959
5038e5741b