***************************************************** /*                   File constructor *****************************************************
function File(chunks, name, opts) {
      opts = opts || {}
      var a = Blob.call(this, chunks, opts) || this
      a.name = name
      a.lastModifiedDate = opts.lastModified ? new Date(opts.lastModified) : new Date
      a.lastModified = +a.lastModifiedDate
      
      return a
    }