Two problems are fixed:
* `isArgumentsLocalBinding` did only `PropertyAccessExpression`, now
it's also doing `PropertyAssignment` (doesn't affect other files,
since it's only used in the emitter).
* `visitShorthandPropertyAssignment` should call `visitIdentifier` on
the synthesized id. (For completion it might be better to make it
visit the the original?)
Fixes#38594.
