ChangeScreen2: Disable Ctrl-Enter while 'Post' is disabled

Ctrl-Enter is the keyboard shortcut for the 'Post' button,
which is temporarily disabled at open while draft comments
are loaded into the box and the input object.

Commit bb50707f0c modified the Post
button to be disabled until the drafts are loaded. If post happens
before this finishes the drafts are not sent, but the user probably
wants them included.

Change-Id: I0fc5009d4dd89ab91e95c4e197146a4b05f830af

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/ReplyBox.java

@@ -124,7 +124,9 @@ class ReplyBox extends Composite {
           if ((e.getCharCode() == '\n' || e.getCharCode() == KEY_ENTER)
               && e.isControlKeyDown()) {
             e.preventDefault();
-            onPost(null);
+            if (post.isEnabled()) {
+              onPost(null);
+            }
           }
         }
       },