nl_tokens: Finds all File instances in formData and creates a new File instance whose storage is forced to be a Blob instead of being backed by a file on disk . That works around a bug in Chrome where File instances with has_backing_file flag cannot be sent over a process boundary when site isolation is on .
pl_tokens: function patchFileObjects ( formData ) { // There are several landmines to avoid when making file uploads work on all browsers: // - the `new File()` constructor trick breaks file uploads on Safari 10 in a way that's //   impossible to detect: it will send empty files in the multipart/form-data body. //   Therefore we need to detect Chrome. // - IE11 and Edge don't support the `new File()` constructor at all. It will throw exception, //   so it's detectable by the `supportsFileConstructor` code. // - `window.chrome` exists also on Edge (!), `window.chrome.webstore` is only in Chrome and //   not in other Chromium based browsers (which have the site isolation bug, too). if ( ! window . chrome || ! supportsFileConstructor ) { return ; } for ( let i = 0 ; i < formData . <mask> ; i ++ ) { const val = getFileValue ( formData [ i ] [ 1 ] ) ; if ( val ) { formData [ i ] [ 1 ] = new File ( [ val ] , val . name , { type : val . type } ) ; } } }