Reapply "Fixes to eventhandler and HTTP""

runtime/bin/socket.cc

Index: runtime/bin/socket.cc
diff --git a/runtime/bin/socket.cc b/runtime/bin/socket.cc
index e0e82420b8f7461396e27d514adb8234aaf33888..2013e093efa492699775419ceeeebb0b26b7318d 100644
--- a/runtime/bin/socket.cc
+++ b/runtime/bin/socket.cc
@@ -187,7 +187,7 @@ void FUNCTION_NAME(Socket_WriteList)(Dart_NativeArguments args) {
       Dart_PropagateError(result);
     }
     bytes_written = Socket::Write(socket, buffer, length);
-    total_bytes_written = bytes_written;
+    if (bytes_written > 0) total_bytes_written = bytes_written;
   } else {
     // Send data in chunks of maximum 16KB.
     const intptr_t max_chunk_length =
@@ -206,7 +206,7 @@ void FUNCTION_NAME(Socket_WriteList)(Dart_NativeArguments args) {
       }
       bytes_written =
           Socket::Write(socket, reinterpret_cast<void*>(buffer), chunk_length);
-      total_bytes_written += bytes_written;
+      if (bytes_written > 0) total_bytes_written += bytes_written;
     } while (bytes_written > 0 && total_bytes_written < length);
     delete[] buffer;
   }