Make ProgressInidcatorConnector use VProgressIndicator (#11925)

When ProgressBar was split out from ProgressIndicator,
ProgressIndicatorConnector was accidentally left inheriting the
VProgressBar widget from ProgressBarConnector instead of using its own
VProgressIndicator.

Change-Id: Ie7c5d3b68af871d5eb2a86f3d720af3b23048793

client/src/com/vaadin/client/ui/progressindicator/ProgressIndicatorConnector.java

@@ -19,6 +19,7 @@ package com.vaadin.client.ui.progressindicator;
 import com.google.gwt.user.client.Timer;
 import com.vaadin.client.communication.StateChangeEvent;
 import com.vaadin.client.ui.VProgressBar;
+import com.vaadin.client.ui.VProgressIndicator;
 import com.vaadin.shared.ui.Connect;
 import com.vaadin.shared.ui.progressindicator.ProgressIndicatorServerRpc;
 import com.vaadin.shared.ui.progressindicator.ProgressIndicatorState;
@@ -61,6 +62,11 @@ public class ProgressIndicatorConnector extends ProgressBarConnector {
         }
     }
 
+    @Override
+    public VProgressIndicator getWidget() {
+        return (VProgressIndicator) super.getWidget();
+    }
+
     @Override
     public void onUnregister() {
         super.onUnregister();