Propagate channelWritabilityChanged() through the pipeline after flushing. Related to [#1861]

handler/src/main/java/io/netty/handler/stream/ChunkedWriteHandler.java

@@ -129,11 +129,6 @@ public class ChunkedWriteHandler
         }
     }
 
-    @Override
-    public void read(ChannelHandlerContext ctx) {
-        ctx.read();
-    }
-
     @Override
     public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
         queue.add(new PendingWrite(msg, promise));
@@ -159,6 +154,7 @@ public class ChunkedWriteHandler
             // channel is writable again try to continue flushing
             doFlush(ctx);
         }
+        ctx.fireChannelWritabilityChanged();
     }
 
     private void discard(Throwable cause) {