[XHR] Fix a XHR-stream test script.

LayoutTests/http/tests/xmlhttprequest/resources/slow-failure.cgi

Index: LayoutTests/http/tests/xmlhttprequest/resources/slow-failure.cgi
diff --git a/LayoutTests/http/tests/xmlhttprequest/resources/slow-failure.cgi b/LayoutTests/http/tests/xmlhttprequest/resources/slow-failure.cgi
index 8b2b92f6371bee97be4903a26e73b2c5423b7ead..bd09f32fb74b74f3f8485125d1c80676cae76304 100755
--- a/LayoutTests/http/tests/xmlhttprequest/resources/slow-failure.cgi
+++ b/LayoutTests/http/tests/xmlhttprequest/resources/slow-failure.cgi
@@ -1,5 +1,9 @@
 #!/usr/bin/perl
 
+# This script outputs a broken transfer-encoded response. In order to deliver
+# didReceiveResponse to the client (i.e. XHR), we send a small valid chunk
+# first, wait a while and then send an invalid chunk.
+
 use IO::Socket;
 
 $| = 1;
@@ -7,8 +11,10 @@ $| = 1;
 autoflush STDOUT 1;
 
 print "Content-Type: text/html; charset=us-ascii\n";
+print "X-Content-Type-Options: nosniff\n";
 print "Transfer-encoding: chunked\n\n";
 
+print "5\nhello\n";
 sleep 2;
 
 print "hoge\nfuga\n";