function readMore() {
    // Only Array and string have length
    while (pos < /** @type {?} */ (input).length) {
      if (!utils.isJsonWhitespace(input[pos])) {
        return true;
      }
      pos++;
      parser.streamPos_++;
    }
    return false;
  }
Advances to the first non-whitespace input character.

@return {boolean} return false if no more non-whitespace input character