JavaScript engines

[Johan Dahlin <johan gnome org>]

We need to have this discussion sooner or later, seems like sooner
is now required as Robert proposed to have Seed included in Gnome.

First of all, I think most of us agrees that it would be a mistake to depend 
on two different JavaScript bindings in GNOME, we need to chose one and 
stick to that one.

What we currently have are the following two engines:

* Gjs - binding for Spidermonkey, part of Gecko/Mozilla
* Seed - binding for JSCore, part of Webkit/Apple

Before attempting to list the different reasons for using one over the other 
we need to decide what are the requirements for an engine using JavaScript.
For instance, points such as:

- External dependencies
- Interpretor implementation language
- Memory usage
- Speed
- APIs (Extending & Embedding)
- Documentation
- License
- Feature completeness
- API stability (both in JS engine & bindings)
- JavaScript language extensions

Would be useful to help out in this discussion.

[Note: I have contributed patches to Gjs]

Johan