Review

class JSTypeRegistry {
  /**
   * Gets the greatest subtype of the {@code type} that has a property
   * {@code propertyName} defined on it.
   */
  public JSType getGreatestSubtypeWithProperty(
      JSType type, String propertyName) {
    if (greatestSubtypeByProperty.containsKey(propertyName)) {
      return greatestSubtypeByProperty.get(propertyName)
          .getGreatestSubtype(type);
    }
    if (typesIndexedByProperty.containsKey(propertyName)) {
      JSType built = typesIndexedByProperty.get(propertyName).build();
      greatestSubtypeByProperty.put(propertyName, built);
      return built.getGreatestSubtype(type);
    }
    return getNativeType(NO_TYPE);
  }

}