Tests scoped variable in Runtime.evaluate
Evaluating 'let a = 42;'
{
    type : undefined
}
Evaluating 'a'
{
    description : 42
    type : number
    value : 42
}
Evaluating 'let a = 239;'
{
    exceptionDetails : {
        columnNumber : 0
        exception : {
            className : SyntaxError
            description : SyntaxError: Identifier 'a' has already been declared
            objectId : <objectId>
            subtype : error
            type : object
        }
        exceptionId : <exceptionId>
        lineNumber : 0
        scriptId : <scriptId>
        text : Uncaught
    }
    result : {
        className : SyntaxError
        description : SyntaxError: Identifier 'a' has already been declared
        objectId : <objectId>
        subtype : error
        type : object
    }
}
Evaluating 'a'
{
    description : 42
    type : number
    value : 42
}