nl_tokens: Handles a progress event being proxied back from the iframe page .
pl_tokens: function onprogress ( <mask> ) { debug ( 'got "progress" event: %o' , data ) ; const xhr = requests [ data . callbackId ] ; if ( xhr ) { const prog = new ProgressEvent ( 'progress' , data ) ; const target = data . upload ? xhr . upload : xhr ; target . dispatchEvent ( prog ) ; } }