Make event-handlers edge-triggered and move socket-state to Dart.

sdk/lib/io/secure_socket.dart

Index: sdk/lib/io/secure_socket.dart
diff --git a/sdk/lib/io/secure_socket.dart b/sdk/lib/io/secure_socket.dart
index b3c70636f8d4c1ae9138e54e91d8194c2b57df10..241da82cbbbede6f58e2dec65357b9bab9418de6 100644
--- a/sdk/lib/io/secure_socket.dart
+++ b/sdk/lib/io/secure_socket.dart
@@ -973,7 +973,8 @@ class _RawSecureSocket extends Stream<RawSocketEvent>
 
   _sendReadEvent() {
     _pendingReadEvent = false;
-    if (_readEventsEnabled &&
+    if (_status != CLOSED &&
+        _readEventsEnabled &&
         _pauseCount == 0 &&
         _secureFilter != null &&
         !_secureFilter.buffers[READ_PLAINTEXT].isEmpty) {
@@ -1164,16 +1165,16 @@ class _ExternalBuffer {
     int written = 0;
     int toWrite = linearFree;
     // Loop over zero, one, or two linear data ranges.
-    while (toWrite > 0) {
+    do {
       // Source returns at most toWrite bytes, and it returns null when empty.
       var inputData = getData(toWrite);
-      if (inputData == null) break;
+      if (inputData == null || inputData.length == 0) break;
       var len = inputData.length;
       data.setRange(end, end + len, inputData);
       advanceEnd(len);
       written += len;
       toWrite = linearFree;
-    }
+    } while (toWrite > 0);
     return written;
   }