[XBL] ECMAScript Syntax

Dear XBL experts,

This email comments on the 7 September 2006 LCWD of XBL 2.0.

In many examples in the specification, in particular in Section 2.3, a 
syntax for ECMAScript definition of functions is used:

<implementation>
({
functionName: function() {
}
})
</implementation>

Is this standard ECMAScript notation ? Could you explain it or provide a 
link to it ? What is the meaning of "({" ?
The get/set fonction in that section don't use the ':' ? Is it a typo ? 
If yes please fix it, otherwise highlight and explain this difference 
with the other functions.

Cyril Concolato