A 
    
    TileDiscardPolicy specifying that tile images should never be discard.
Methods
    Determines if the discard policy is ready to process images.
Returns:
    True if the discard policy is ready to process images; otherwise, false.
    
    Given a tile image, decide whether to discard that image.
    
| Name | Type | Description | 
|---|---|---|
| image | HTMLImageElement | An image to test. | 
Returns:
    True if the image should be discarded; otherwise, false.
    
