Previously, `UmdReflectionHost` would only recognize re-exports of the
form `__export(someIdentifier)` and not `__export(require('...'))`.
However, it is possible in some UMD variations to have the latter format
as well. See discussion in https://github.com/angular/angular/pull/34254/files#r359515373
This commit adds support for re-export of the form
`__export(require('...'))` in UMD.
PR Close #34512