DefaultPromise StackOverFlowException

Motivation:
When the ImmediateEventExecutor is in use it is possible to get a StackOverFlowException if when a promise completes a new listener is added to that promise.

Modifications:
- Protect against the case where LateListeners.run() smashes the stack.

Result:
Fixes https://github.com/netty/netty/issues/4395

common/src/main/java/io/netty/util/concurrent/DefaultPromise.java

@@ -836,7 +836,8 @@ public class DefaultPromise<V> extends AbstractFuture<V> implements Promise<V> {
 
         @Override
         public void run() {
-            if (listeners == null) {
+            final EventExecutor executor = executor();
+            if (listeners == null || executor == ImmediateEventExecutor.INSTANCE) {
                 for (;;) {
                     GenericFutureListener<?> l = poll();
                     if (l == null) {
@@ -847,7 +848,7 @@ public class DefaultPromise<V> extends AbstractFuture<V> implements Promise<V> {
             } else {
                 // Reschedule until the initial notification is done to avoid the race condition
                 // where the notification is made in an incorrect order.
-                execute(executor(), this);
+                execute(executor, this);
             }
         }
     }

common/src/test/java/io/netty/util/concurrent/DefaultPromiseTest.java

@@ -143,6 +143,38 @@ public class DefaultPromiseTest {
         testListenerNotifyLater(2);
     }
 
+    @Test(timeout = 2000)
+    public void testPromiseListenerAddWhenCompleteFailure() throws Exception {
+        testPromiseListenerAddWhenComplete(new RuntimeException());
+    }
+
+    @Test(timeout = 2000)
+    public void testPromiseListenerAddWhenCompleteSuccess() throws Exception {
+        testPromiseListenerAddWhenComplete(null);
+    }
+
+    private static void testPromiseListenerAddWhenComplete(Throwable cause) throws InterruptedException {
+        final CountDownLatch latch = new CountDownLatch(1);
+        final Promise<Void> promise = new DefaultPromise<Void>(ImmediateEventExecutor.INSTANCE);
+        promise.addListener(new FutureListener<Void>() {
+            @Override
+            public void operationComplete(Future<Void> future) throws Exception {
+                promise.addListener(new FutureListener<Void>() {
+                    @Override
+                    public void operationComplete(Future<Void> future) throws Exception {
+                        latch.countDown();
+                    }
+                });
+            }
+        });
+        if (cause == null) {
+            promise.setSuccess(null);
+        } else {
+            promise.setFailure(cause);
+        }
+        latch.await();
+    }
+
     private static void testListenerNotifyLater(final int numListenersBefore) throws Exception {
         EventExecutor executor = new TestEventExecutor();
         int expectedCount = numListenersBefore + 2;