Add negative False Start tests.

Extend the False Start tests to optionally send an alert (thus avoiding
deadlock) before waiting for the out-of-order app data. Based on whether the
peer shuts off the connection before or after sending app data, we can
determine whether the peer False Started by observing purely external effects.

Change-Id: I8b9fecc29668e0b0c34b5fd19d0f239545011bae
Reviewed-on: https://boringssl-review.googlesource.com/4213
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index 73aeb82..df0db4d 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -506,6 +506,13 @@
 	// from the peer.
 	ExpectFalseStart bool
 
+	// AlertBeforeFalseStartTest, if non-zero, causes the server to, on full
+	// handshakes, send an alert just before reading the application data
+	// record to test False Start. This can be used in a negative False
+	// Start test to determine whether the peer processed the alert (and
+	// closed the connection) before or after sending app data.
+	AlertBeforeFalseStartTest alert
+
 	// SSL3RSAKeyExchange causes the client to always send an RSA
 	// ClientKeyExchange message without the two-byte length
 	// prefix, as if it were SSL3.