Review

class AliasStrings {
  /**
   * Looks up the {@link StringInfo} object for a JavaScript string. Creates
   * it if necessary.
   */
  private StringInfo getOrCreateStringInfo(String string) {
    StringInfo info = stringInfoMap.get(string);
    if (info == null) {
      info = new StringInfo(stringInfoMap.size());
      stringInfoMap.put(string, info);
    }
    return info;
  }

}