For now argument forwarding doesn't allow some keywords like `true` as a
method name.

To bypass the issue, fallback to `define_method` if method names are
Ruby reserved keywords.

https://bugs.ruby-lang.org/issues/16854

```ruby
class Works
  def true(*args)
    puts(*args)
  end
end

Works.new.true 1, 2, 3
# => 1, 2, 3

class WontWork
  def true(...)
    puts(...)
  end
end
```

```
% ruby a.rb
a.rb:12: syntax error, unexpected ..., expecting ')'
  def true(...)
a.rb:13: unexpected ...
a.rb:15: syntax error, unexpected `end', expecting end-of-input
```