Fix a renderer crash while processing FTP directory listing.

net/ftp/ftp_directory_listing_buffer.cc

Index: net/ftp/ftp_directory_listing_buffer.cc
diff --git a/net/ftp/ftp_directory_listing_buffer.cc b/net/ftp/ftp_directory_listing_buffer.cc
index 41daeb45048976c0592f36f92760de8daaa19c43..8399f131ab8a94197b9c784a3c00a548c08dc428 100644
--- a/net/ftp/ftp_directory_listing_buffer.cc
+++ b/net/ftp/ftp_directory_listing_buffer.cc
@@ -149,7 +149,7 @@ int FtpDirectoryListingBuffer::OnEndOfInput() {
   }
 
   if (parsers_.size() != 1) {
-    DCHECK(!current_parser_);
+    current_parser_ = NULL;
 
     // We may hit an ambiguity in case of listings which have no entries. That's
     // fine, as long as all remaining parsers agree that the listing is empty.