function skipWhitespace() {
    // Only Array and string have length
    while (i < /** @type {?} */ (input).length) {
      if (utils.isJsonWhitespace(input[i])) {
        i++;
        parser.pos_++;
        continue;
      }
      break;
    }
  }
Skip as many whitespaces as possible, and increments current index of
stream to next available char.