[webdatabase] SQLError codes

[João Eiras]

Hi.
The IDL for SQLError defines a code property with the values described at 
http://dev.w3.org/html5/webdatabase/#errors-and-exceptions
Currently, the table with those values only has numbers (error codes) and 
textual descriptionss.
It would be nice if those errors were enumerated in the SQLError interface, and 
be given a persistent name, like with DOMException.

interface SQLError {
  readonly attribute unsigned long code;
  readonly attribute DOMString message;

  static const unsigned long TRANSACTION_FAILED = 0;
  static const unsigned long DATABASE_ERROR = 1;
  ....
};

Thank you.