Auto-prepend BOM in IE10+

The last commit fixes some BOM prepending issues but it doesn't actually
add support for IE. This commit adds full auto-prepend BOM support for
IE.

Author: eligrey

FileSaver.js

@@ -1,6 +1,6 @@
 /* FileSaver.js
  * A saveAs() FileSaver implementation.
- * 2015-05-07.1
+ * 2015-05-07.2
  *
  * By Eli Grey, http://eligrey.com
  * License: X11/MIT
@@ -12,16 +12,10 @@
 
 /*! @source http://purl.eligrey.com/github/FileSaver.js/blob/master/FileSaver.js */
 
-var saveAs = saveAs
-  // IE 10+ (native saveAs)
-  || (typeof navigator !== "undefined" &&
-      navigator.msSaveOrOpenBlob && navigator.msSaveOrOpenBlob.bind(navigator))
-  // Everyone else
-  || (function(view) {
+var saveAs = saveAs || (function(view) {
 	"use strict";
 	// IE <10 is explicitly unsupported
-	if (typeof navigator !== "undefined" &&
-	    /MSIE [1-9]\./.test(navigator.userAgent)) {
+	if (typeof navigator !== "undefined" && /MSIE [1-9]\./.test(navigator.userAgent)) {
 		return;
 	}
 	var
@@ -81,7 +75,15 @@ var saveAs = saveAs
 				}
 			}
 		}
+		, auto_bom = function(blob) {
+			// prepend BOM for UTF-8 XML and text/* types (including HTML)
+			if (/^\s*(?:text\/\S*|application\/xml|\S*\/\S*\+xml)\s*;.*charset\s*=\s*utf-8/i.test(blob.type)) {
+				return new Blob(["\ufeff", blob], {type: blob.type});
+			}
+			return blob;
+		}
 		, FileSaver = function(blob, name) {
+			blob = auto_bom(blob);
 			// First try a.download, then web filesystem, then object URLs
 			var
 				  filesaver = this
@@ -125,10 +127,6 @@ var saveAs = saveAs
 			if (!name) {
 				name = "download";
 			}
-			// prepend BOM for UTF-8 XML and text/* types (including HTML)
-			if (/^\s*(?:text\/\S*|application\/xml|\S*\/\S*\+xml)\s*;.*charset\s*=\s*utf-8/i.test(blob.type)) {
-				blob = new Blob(["\ufeff", blob], {type: blob.type});
-			}
 			if (can_use_save_link) {
 				object_url = get_URL().createObjectURL(blob);
 				save_link.href = object_url;
@@ -211,6 +209,13 @@ var saveAs = saveAs
 			return new FileSaver(blob, name);
 		}
 	;
+	// IE 10+ (native saveAs)
+	if (typeof navigator !== "undefined" && navigator.msSaveOrOpenBlob) {
+		return function(blob, name) {
+			return navigator.msSaveOrOpenBlob(auto_bom(blob), name);
+		};
+	}
+
 	FS_proto.abort = function() {
 		var filesaver = this;
 		filesaver.readyState = filesaver.DONE;
@@ -245,4 +250,4 @@ if (typeof module !== "undefined" && module.exports) {
   define([], function() {
     return saveAs;
   });
-}
+}