[webidl] definition of const string literal

[Max Froumentin]

Hi, 

The grammar in http://dev.w3.org/2006/webapi/WebIDL/ prevents declarations such 
as:

const DOMString foo = "bar";

because the "ConstExp" rule [1] only allows a number, or "TRUE" or "FALSE".
Is it an omission?

Max.

[1] http://dev.w3.org/2006/webapi/WebIDL/#prod-ConstExpr