Fix issues with Socket shutdown.

runtime/bin/socket_patch.dart

Index: runtime/bin/socket_patch.dart
diff --git a/runtime/bin/socket_patch.dart b/runtime/bin/socket_patch.dart
index c866977f29ad60b7ac3b771a39e57f68add1782f..dfbd46589e564f18d875c00975941125320c3c9d 100644
--- a/runtime/bin/socket_patch.dart
+++ b/runtime/bin/socket_patch.dart
@@ -287,6 +287,7 @@ class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
   bool isClosed = false;
   bool isClosing = false;
   bool isClosedRead = false;
+  bool closedReadEventSent = false;
   bool isClosedWrite = false;
   Completer closeCompleter = new Completer.sync();
 
@@ -694,6 +695,7 @@ class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
   }
 
   void issueReadEvent() {
+    if (closedReadEventSent) return;
     if (readEventIssued) return;
     readEventIssued = true;
     void issue() {
@@ -701,10 +703,11 @@ class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
       if (isClosing) return;
       if (!sendReadEvents) return;
       if (available == 0) {
-        if (isClosedRead) {
+        if (isClosedRead && !closedReadEventSent) {
           if (isClosedWrite) close();
           var handler = eventHandlers[CLOSED_EVENT];
           if (handler == null) return;
+          closedReadEventSent = true;
           handler();
         }
         return;
@@ -860,7 +863,7 @@ class _NativeSocket extends _NativeSocketNativeWrapper with _ServiceObject {
 
   void shutdownWrite() {
     if (!isClosing && !isClosed) {
-      if (isClosedRead) {
+      if (closedReadEventSent) {
         close();
       } else {
         sendToEventHandler(1 << SHUTDOWN_WRITE_COMMAND);