Android本机浏览器中的Ajax FileUpload失败（Webkit 534.30）

Question

我使用以下代码将从画布导出的文件上传到服务器。它适用于Chrome for Android，但使用带有webkit版本534.30的原生Android浏览器上传失败。

var canvas; // a canvas with an image jpg or png
var dataUrl = canvas.toDataURL();
var file = dataURLtoBlob(dataUrl); //source: https://github.com/blueimp/JavaScript-Canvas-to-Blob


                    var formdata = new FormData();
        formdata.append("image", file);
        var xhrNativeObject = new XMLHttpRequest();
        // Upload progress listener
        xhrNativeObject.upload.addEventListener("progress", function (event) {
            if (event.lengthComputable) {
                var position = event.loaded || event.position;
                var total = event.total;
                var xhrPercentComplete = (position / total * 100 | 0);
                console.log(xhrPercentComplete, position, total);
            }
        }, false);

        xhrNativeObject.open("post", url, true);
        xhrNativeObject.onload = function (event) {

            var targetResponse = event.currentTarget;
            if ((targetResponse.readyState == 4) && (targetResponse.status == 200)) {
                var obj = JSON.parse(targetResponse.responseText);
                console.log(obj);
            } else {
                console.log("error");
            }

        }

        // send the file
        xhrNativeObject.send(formdata);

文件到达服务器时一直是空的。

如何上传从Android原生浏览器上的Canvas导出的文件？