Applies the change to the script. The change is always a substring (change_pos, change_pos + change_len) being replaced with a completely different string new_str. This API is a legacy and is obsolete.  @param {Script} script that is being changed @param {Array} change_log a list that collects engineer-readable description of what happened.
function ApplySingleChunkPatch(script, change_pos, change_len, new_str,
      change_log) {
    var old_source = script.source;

    // Prepare new source string.
    var new_source = old_source.substring(0, change_pos) +
        new_str + old_source.substring(change_pos + change_len);

    return ApplyPatchMultiChunk(script,
        [ change_pos, change_pos + change_len, change_pos + new_str.length],
        new_source, false, change_log);
  }