Fix sync xhr in Firefox

dist/xhook.js

@@ -446,6 +446,9 @@ XHookHttpRequest = window[XMLHTTP] = function() {
     _ref1 = ['type', 'timeout', 'withCredentials'];
     for (_j = 0, _len1 = _ref1.length; _j < _len1; _j++) {
       k = _ref1[_j];
+      if (k === 'withCredentials' && !request.async) {
+        continue;
+      }
       modk = k === "type" ? "responseType" : k;
       if (modk in facade) {
         request[k] = facade[modk];

src/xhook.coffee

@@ -370,6 +370,7 @@ XHookHttpRequest = window[XMLHTTP] = ->
   facade.send = (body) ->
     #read xhr settings before hooking
     for k in ['type', 'timeout', 'withCredentials']
+      continue if (k is 'withCredentials' and not request.async)
       modk = if k is "type" then "responseType" else k
       request[k] = facade[modk] if modk of facade
 

test/tests.js

@@ -59,4 +59,11 @@ describe('xhook', function() {
     };
     xhr.send();
   });
+
+  it('sync XHR should not fail', function(done) {
+    var xhr = new XMLHttpRequest();
+    xhr.open('GET', '../example/example1.txt', false);
+    xhr.send();
+    done();
+  });
 });