Tidy up extensions stuff and drop fastradio support.

Fastradio was a trick where the ClientHello was padding to at least 1024
bytes in order to trick some mobile radios into entering high-power mode
immediately. After experimentation, the feature is being dropped.

This change also tidies up a bit of the extensions code now that
everything is using the new system.

Change-Id: Icf7892e0ac1fbe5d66a5d7b405ec455c6850a41c
Reviewed-on: https://boringssl-review.googlesource.com/5466
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index bad3ebe..fb78ef1 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -621,10 +621,6 @@
 	// across a renego.
 	RequireSameRenegoClientVersion bool
 
-	// RequireFastradioPadding, if true, requires that ClientHello messages
-	// be at least 1000 bytes long.
-	RequireFastradioPadding bool
-
 	// ExpectInitialRecordVersion, if non-zero, is the expected
 	// version of the records before the version is determined.
 	ExpectInitialRecordVersion uint16
@@ -736,6 +732,10 @@
 	// ExpectNewTicket, if true, causes the client to abort if it does not
 	// receive a new ticket.
 	ExpectNewTicket bool
+
+	// RequireClientHelloSize, if not zero, is the required length in bytes
+	// of the ClientHello /record/. This is checked by the server.
+	RequireClientHelloSize int
 }
 
 func (c *Config) serverInit() {