FormData and other xhr send types are converted to plain objects

[green3g]

FormData is a valid option for xhr requests and is useful for uploading files. In addition there are other types, like Blob that may be sent via xhr. https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/send

If I have an xhr request like this:

        const data = new FormData();
        for (let i = 0; i < files.length; i++) {
            data.append(i, files.item(i));
        }

            const req = new XMLHttpRequest();
            req.open('POST', this.properties.url, true);
            req.onload = function () {
                if (req.status === 200) {
                    resolve(JSON.parse(req.responseText));
                } else {
                    reject(req);
                }
            };
            req.onerror = reject;
            req.send(data);

The fixture request variable does not allow accessing the FormData properties and fails with

// throws error TypeError: 'entries' called on an object that does not implement interface FormData.

The solution is something like checking to see of the data is an instance of the various data types that can be passed to send. Will submit a pr to demonstrate.

[chasenlehara]

This should be fixed in 1.2.2. Thanks @roemhildtg!