remove _marshal and _demarshal functions

[calvinmetcalf]

postMessage serializes naturally via structured cloning which is a better algorithm than JSON.stringify as it can handle circular dependencies

[padolsey]

We use structured cloning if it's available. By default the _marshal and _demarshal methods are just pass-throughs:

// ... L147
    _marshal: function(v) {
        return v;
    },
    _demarshal: function(v) {
        return v;
    },

We only use JSON methods if we get a 'pingback:objectTransferSupport=NO' from the worker (src):

// ... L272
    if (data === 'pingback:objectTransferSupport=NO') {
        this._marshal = function(o) { return JSON.stringify(o); };
        this._demarshal = function(o) { return JSON.parse(o); };
    }

This is misleading though (a mistake of mine during development), it should in-fact be called 'pingback:structuredCloningSupport=NO' -- I'll make sure to change that soon.

To detect support for structured-cloning we send a message postMessage(['PING']) and if the worker receives it as an Array then we know it supports structured-cloning, otherwise the worker receives it as a string "PING". And in that case we serialize/deserialize JSON from that point onwards.

[calvinmetcalf]

Are there browsers that support workers but not structured cloning or is this for use in the the fallbacks?

[padolsey]

This is only as a fallback. AFAICT Safari 4 supports Worker, but not Blob/BlobBuilder, and only allows strings to be passed via postMessage -- so this fallback is used there.

[calvinmetcalf]

Are you able to test it that far back, Sauce labs only goes back to Safari 5 (workers but no window.URL)

[padolsey]

Not sure how reliable this is but I tested using version 4 from here http://michelf.ca/projects/multi-safari/

Right now operative doesn't work in Sf4 for other reasons which I'm now looking into.

[calvinmetcalf]

ah well this can be closed, I was going through the code trying to figure out if the transferable objects issue needed to be that they should be added to the code or the documentation.

[padolsey]

Fixed naming confusion here https://github.com/padolsey/operative/commit/9033a06aaa8acc35f251f620c04f04096c13978e