Make sure we never give a NULL context to requests.

Use a default context instead. This allows apps without a context
management to still have cookies and HTTP digest authentication (without
persistence to disk).

First part of fix to #10239 (it also needs changes in WebKit).

src/kits/network/libnetapi/UrlProtocolRoster.cpp

@@ -17,10 +17,16 @@
 #include <Debug.h>
 
 
+static BUrlContext gDefaultContext;
+
+
 /* static */ BUrlRequest*
 BUrlProtocolRoster::MakeRequest(const BUrl& url,
 	BUrlProtocolListener* listener, BUrlContext* context)
 {
+	if(context == NULL)
+		context = &gDefaultContext;
+
 	// TODO: instanciate the correct BUrlProtocol using add-on interface
 	if (url.Protocol() == "http") {
 		return new(std::nothrow) BHttpRequest(url, false, "HTTP", listener,