Tests how Runtime.evaluate handles uniqueContextId argument
token in context 1: context 1
token in context 2: context 2
{
    error : {
        code : -32602
        message : contextId and uniqueContextId are mutually exclusive
    }
    id : <messageId>
}
{
    error : {
        code : -32602
        message : invalid uniqueContextId
    }
    id : <messageId>
}
{
    error : {
        code : -32602
        message : uniqueContextId not found
    }
    id : <messageId>
}