external function IsAssetSpecReady(bucketName as String, assetID as ID) as Boolean
This function is used to determine whether or not an asset spec has been successfully loaded (and is ready for use) in a particular prop bucket. This function is often used in conjunction with
AddAssetSpec() with a timer for polling to do something when "ready". Using the newer external function
AddAssetSpecWithCB() is the preferred method to add asset specs since it eliminates the need to poll.