Fix WebSocketPair pumpTo() behavior when other end is dropped.

This should be treated as the other end disconnecting, not an error.

This is not related to tables but is needed for the Cloudflare Workers runtime change I'm working on that also uses tables... so I'm throwing it into the same PR.

c++/src/kj/compat/http.c++

@@ -2828,7 +2828,11 @@ private:
 
     void abort() override {
       canceler.cancel("other end of WebSocketPipe was destroyed");
-      fulfiller.reject(KJ_EXCEPTION(DISCONNECTED, "other end of WebSocketPipe was destroyed"));
+
+      // abort() is called when the pipe end is dropped. This should be treated as disconnecting,
+      // so pumpTo() should complete normally.
+      fulfiller.fulfill();
+
       pipe.endState(*this);
       pipe.abort();
     }