Workaround an exception in Gecko when using Blob.prototype.slice as widget property.

The exception thrown was "Illegal operation on WrappedNative prototype
object" and occurs due to the proxying of the jQuery UI widget methods.

Author: blueimp

js/jquery.fileupload.js

@@ -1,5 +1,5 @@
 /*
- * jQuery File Upload Plugin 5.31.4
+ * jQuery File Upload Plugin 5.31.5
  * https://github.com/blueimp/jQuery-File-Upload
  *
  * Copyright 2010, Sebastian Tschan
@@ -233,8 +233,10 @@
             'forceIframeTransport'
         ],
 
-        _blobSlice: window.Blob && (Blob.prototype.slice ||
-            Blob.prototype.webkitSlice || Blob.prototype.mozSlice),
+        _blobSlice: function () {
+            var slice = this.slice || this.webkitSlice || this.mozSlice;
+            return slice.apply(this, arguments);
+        },
 
         _BitrateTimer: function () {
             this.timestamp = ((Date.now) ? Date.now() : (new Date()).getTime());