Fix change-star in change view

Regression caused by 08ab3aa2 -- the change-star element no longer makes
API calls, instead relying on the parent component.

Bug: Issue 9511
Change-Id: I26faee7ab9158687ec939c48592f3a263cffc93e

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.html

@@ -362,7 +362,9 @@ limitations under the License.
         <div class="headerTitle">
           <gr-change-star
               id="changeStar"
-              change="{{_change}}" hidden$="[[!_loggedIn]]"></gr-change-star>
+              change="{{_change}}"
+              on-toggle-star="_handleToggleStar"
+              hidden$="[[!_loggedIn]]"></gr-change-star>
           <div class="changeStatuses">
             <template is="dom-repeat" items="[[_changeStatuses]]" as="status">
               <gr-change-status

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.js

@@ -1623,5 +1623,10 @@
     _resetReplyOverlayFocusStops() {
       this.$.replyOverlay.setFocusStops(this.$.replyDialog.getFocusStops());
     },
+
+    _handleToggleStar(e) {
+      this.$.restAPI.saveChangeStarred(e.detail.change._number,
+          e.detail.starred);
+    },
   });
 })();

polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.html

@@ -1735,5 +1735,18 @@ limitations under the License.
       assert.isTrue(setStub.calledOnce);
       assert.isTrue(setStub.calledWith(101, 'test-project'));
     });
+
+    test('_handleToggleStar called when star is tapped', () => {
+      element._change = {
+        owner: {_account_id: 1},
+        starred: false,
+      };
+      element._loggedIn = true;
+      const stub = sandbox.stub(element, '_handleToggleStar');
+      flushAsynchronousOperations();
+
+      MockInteractions.tap(element.$.changeStar.$$('button'));
+      assert.isTrue(stub.called);
+    });
   });
 </script>