Clarify what are valid values for "identifier" in #call

[judofyr]

Context#call(identifier, *args) is only tested against these identifiers in the test case:

• "id"
• "a.b.id"
• "CoffeeScript.eval"

However, in the wild (example for Autoprefixer Rails) people are sending full JavaScript code as the "identifier". This works on some backend (Node.js), but fails on others (Duktape). What is the intended behaviour here? Should Duktape support full JavaScript in identifier, or should Autoprefixer Rails be fixed to first define it as a function?

[rafaelfranca]

What is the behavior of other runtimes like mini_racer and therubyracer?

[judofyr]

• RubyRacer: Supports any JavaScript as identifier
• MiniRacer: Also supports any JavaScript as identifier, but it's implemented as eval + JSON.generate(args) (see the TODO in the source) instead being directly serialized into the runtime.

[rafaelfranca]

In that case I believe Duktabe should also support any JavaScript as identifier.

[judofyr]

I'll try to create a PR with updated tests and documentation.