Fixed: CPURLConnection now accepts withCredentials

From the original PR:

CPURLConnection was modified to reduce the withCredentials flag to a file-scope member. This has been done to facilitate use of withCredentials when a developer cannot modify the CPURLConnection manually (e.g. https://github.com/wireload/Ratatosk/blob/master/WLRemoteLink.j, line 466).

Refs #1296, #2138

Foundation/CPURLConnection.j

@@ -27,6 +27,7 @@
 @import "CPURLResponse.j"
 
 var CPURLConnectionDelegate = nil;
+var withCredentials = NO;
 
 /*!
     @class CPURLConnection
@@ -87,6 +88,21 @@ var CPURLConnectionDelegate = nil;
     CPURLConnectionDelegate = delegate;
 }
 
+/*
+    Sets a flag to designate whether async XMLHTTPRequests should allow credentials to be sent or not.
+    This only works with async calls.
+    @param willSendWithCredentials flag to let XMLHTTPRequests to use withCredentials
+*/
++ (void)setWithCredentials:(BOOL)willSendWithCredentials
+{
+    withCredentials = willSendWithCredentials;
+}
+
++ (BOOL)withCredentials
+{
+    return withCredentials;
+}
+
 /*
     Sends a request for the data from a URL. This is the easiest way to obtain data from a URL.
     @param aRequest contains the URL to request the data from
@@ -189,6 +205,8 @@ var CPURLConnectionDelegate = nil;
 {
     _isCanceled = NO;
 
+    _HTTPRequest.setWithCredentials(withCredentials);
+
     try
     {
         _HTTPRequest.open([_request HTTPMethod], [[_request URL] absoluteString], YES);