Reenable revert button when revert is cancelled

Bug: issue 3337
Change-Id: I70b327e30bfca8efe81b2581cd619291ed2b5724
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/RevertAction.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/RevertAction.java
index 3af97f5..47d6cad 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/RevertAction.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/change/RevertAction.java
@@ -22,10 +22,12 @@
 import com.google.gerrit.client.ui.TextAreaActionDialog;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.reviewdb.client.Change;
+import com.google.gwt.event.logical.shared.CloseEvent;
 import com.google.gwt.user.client.ui.Button;
+import com.google.gwt.user.client.ui.PopupPanel;
 
 class RevertAction {
-  static void call(Button b, final Change.Id id, final String revision,
+  static void call(final Button b, final Change.Id id, final String revision,
       final String commitSubject) {
     // TODO Replace ActionDialog with a nicer looking display.
     b.setEnabled(false);
@@ -56,6 +58,12 @@
               }
             });
       }
+
+      @Override
+      public void onClose(CloseEvent<PopupPanel> event) {
+        super.onClose(event);
+        b.setEnabled(true);
+      }
     }.center();
   }
 }