Symbols are not converted to JavaScript strings with .call(*args)

[eregon]

From rails/execjs#110 (comment)

Unlike all other execjs backends, therubyrhino currently does not convert :some_symbol to "some_symbol" when passing it to JavaScript.
I think it would make sense to fix it in this gem.

[eregon]

Another possibility is to have this behavior only for ExecJS in https://github.com/rails/execjs/blob/39118e25f9c2ee40e475ac64653e66be6f4aecd0/lib/execjs/ruby_rhino_runtime.rb#L35.
What do you think is better/makes more sense?