Fix crash when an SSL key-log file couldn't be opened.

net/third_party/nss/ssl/sslsock.c

Index: net/third_party/nss/ssl/sslsock.c
diff --git a/net/third_party/nss/ssl/sslsock.c b/net/third_party/nss/ssl/sslsock.c
index 1823a1ca3faa0be49d628f006d3b1df8adf4fb44..2a93daedd0b07e61e9a8f50cff0d378a66ab95f0 100644
--- a/net/third_party/nss/ssl/sslsock.c
+++ b/net/third_party/nss/ssl/sslsock.c
@@ -2934,11 +2934,15 @@ ssl_SetDefaultsFromEnvironment(void)
 	ev = getenv("SSLKEYLOGFILE");
 	if (ev && ev[0]) {
 	    ssl_keylog_iob = fopen(ev, "a");
-	    if (ftell(ssl_keylog_iob) == 0) {
-		fputs("# SSL/TLS secrets log file, generated by NSS\n",
-		      ssl_keylog_iob);
+	    if (!ssl_keylog_iob) {
+		SSL_TRACE(("Failed to open key log file"));
+	    } else {
+		if (ftell(ssl_keylog_iob) == 0) {
+		    fputs("# SSL/TLS secrets log file, generated by NSS\n",
+			  ssl_keylog_iob);
+		}
+		SSL_TRACE(("SSL: logging pre-master secrets to %s", ev));
 	    }
-	    SSL_TRACE(("SSL: logging pre-master secrets to %s", ev));
 	}
 	ev = getenv("SSLBYPASS");
 	if (ev && ev[0]) {