function HttpStreamSequence(url, encoding) {
  this.url = url;
  this.encoding = encoding;
}
Creates a {@link Sequence} from a file stream, whose elements are chunks of
data as the stream is read. This is an {@link AsyncSequence}, so methods such
as {@link Sequence#reduce} return an {@link AsyncHandle} rather than a value.

@param {string} path A path to a file.
@param {string} encoding The text encoding of the file (e.g., "utf-8").
@return {Sequence} The streamed sequence.