message: Change DisplayObject#hitArea type declaration to support more hit-area classes
diff: +/**
  + * Interface for classes that represent a hit area.
  + *
  + * It is implemented by the following classes:
  + * - {@link PIXI.Circle}
  + * - {@link PIXI.Ellipse}
  + * - {@link PIXI.Polygon}
  + * - {@link PIXI.RoundedRectangle}
  + *
  + * @interface IHitArea
  + * @memberof PIXI
  + */
  +
  +/**
  + * Checks whether the x and y coordinates given are contained within this area
  + *
  + * @method
  + * @name contains
  + * @memberof PIXI.IHitArea#
  + * @param {number} x - The X coordinate of the point to test
  + * @param {number} y - The Y coordinate of the point to test
  + * @return {boolean} Whether the x/y coordinates are within this area
  + */
  +
  /**
  * Default property values of interactive objects
  * Used by {@link PIXI.interaction.InteractionManager} to automatically give all DisplayObjects these properties
  @@ -48,7 +72,7 @@ export default {
  * const sprite = new PIXI.Sprite(texture);
  * sprite.interactive = true;
  * sprite.hitArea = new PIXI.Rectangle(0, 0, 100, 100);
  - * @member {PIXI.Rectangle|PIXI.Circle|PIXI.Ellipse|PIXI.Polygon|PIXI.RoundedRectangle}
  + * @member {PIXI.IHitArea}
  * @memberof PIXI.DisplayObject#
  */
  hitArea: null,
  