Fix #2049

Issue: tc39/ecma262#1461
PR: tc39/ecma262#1470

- indirect eval
- files renaming
- space after comma

Counterpart to language/expressions/object/prop-def-invalid-async-prefix.js.

Spec PR: tc39/ecma262#1372

According to sec-identifiers-static-semantics-assignmenttargettype,
`AssignmentTargetType` of `arguments` and `eval` in non-strict mode code is
`simple`.
sec-update-expressions-static-semantics-early-errors mandates early errors for
`UpdateExpression` if `AssignmentTargetType` is `invalid` or `strict`.

Previously, the early error prohibiting duplicate entries in
UniqueFormalParameters was only tested in terms of async functions. In
one case, this was misattributed to UniqeFormalParameters and only
enforced for strict mode code.

Extend coverage to the other function-creating productions which include
UniqueFormalParameters (i.e. method definitions and non-async arrow
functions), and update the existing tests to more accurately describe
the source of the error.

https://github.com/tc39/test262/pull/2020#issuecomment-456581449

Previous commits restructured the tests for line terminators and made
coverage gaps more apparent. Introduce new files to improve coverage.