Re-add _handleFix to diff comment

Bug: Issue 9492
Change-Id: I58c8dc4e4adb1face8dd32598836395e60f6ecc7

polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js

@@ -449,6 +449,13 @@
       this.fire('comment-discard', this._getEventPayload());
     },
 
+    _handleFix() {
+      this.dispatchEvent(new CustomEvent('create-fix-comment', {
+        bubbles: true,
+        detail: this._getEventPayload(),
+      }));
+    },
+
     _handleDiscard(e) {
       e.preventDefault();
       this.$.reporting.recordDraftInteraction();

polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html

@@ -841,5 +841,16 @@ limitations under the License.
       element.save();
       assert.isTrue(discardStub.called);
     });
+
+    test('_handleFix fires create-fix event', done => {
+      element.addEventListener('create-fix-comment', e => {
+        assert.deepEqual(e.detail, element._getEventPayload());
+        done();
+      });
+      element.isRobotComment = true;
+      flushAsynchronousOperations();
+
+      MockInteractions.tap(element.$$('.fix'));
+    });
   });
 </script>