loadImage(image) {
    let imageState = image.getState();
    if (imageState != ImageState.LOADED && imageState != ImageState.ERROR) {
      image.addEventListener(EventType.CHANGE, this.boundHandleImageChange_);
    }
    if (imageState == ImageState.IDLE) {
      image.load();
      imageState = image.getState();
    }
    return imageState == ImageState.LOADED;
  }
Load the image if not already loaded, and register the image change
listener if needed.
@param {import("../Image.js").default} image Image.
@return {boolean} `true` if the image is already loaded, `false` otherwise.
@protected