Don't use vm.annotation.group

The templates read vm.group() (which returns domainModel.group) and never write
any group, so vm.annotation.group just isn't needed.

The controller modifies domainModel.group is the focused group changes while
creating a new annotation.

vm.annotation.group is still there, we just don't use it anymore, in the future
we should not copy it into vm.annotation at all.

h/static/scripts/directive/annotation.js

@@ -297,11 +297,11 @@ function AnnotationController(
     if (isNew(domainModel)) {
       var newGroup = groups.focused().id;
       var isShared = permissions.isShared(
-        vm.annotation.permissions, vm.annotation.group);
+        vm.annotation.permissions, domainModel.group);
       if (isShared) {
         vm.annotation.permissions = permissions.shared(newGroup);
       }
-      vm.annotation.group = newGroup;
+      domainModel.group = newGroup;
     }
 
     if (drafts.get(domainModel)) {
@@ -482,7 +482,7 @@ function AnnotationController(
     * @returns {Object} The full group object associated with the annotation.
     */
   vm.group = function() {
-    return groups.get(vm.annotation.group);
+    return groups.get(domainModel.group);
   };
 
   /**
@@ -547,7 +547,7 @@ function AnnotationController(
     */
   vm.isShared = function() {
     return permissions.isShared(
-      vm.annotation.permissions, vm.annotation.group);
+      vm.annotation.permissions, domainModel.group);
   };
 
   // Save on Meta + Enter or Ctrl + Enter.
@@ -679,7 +679,7 @@ function AnnotationController(
     if (privacy === 'private') {
       vm.annotation.permissions = permissions.private();
     } else if (privacy === 'shared') {
-      vm.annotation.permissions = permissions.shared(vm.annotation.group);
+      vm.annotation.permissions = permissions.shared(domainModel.group);
     }
   };
 

h/static/scripts/directive/test/annotation-test.js

@@ -1506,14 +1506,18 @@ describe('annotation.js', function() {
         // annotation.
         annotation.id = null;
         var controller = createDirective(annotation).controller;
+        fakeGroups.get = sandbox.stub().returns({id: 'new-group'});
 
         // Change the currently focused group.
         fakeGroups.focused = sinon.stub().returns({id: 'new-group'});
         $rootScope.$broadcast(events.GROUP_FOCUSED);
 
+        var group = controller.group().id;
+
+        assert.isTrue(fakeGroups.get.calledOnce);
+        assert.isTrue(fakeGroups.get.calledWithExactly('new-group'));
         assert.equal(
-          controller.annotation.group,
-          'new-group',
+          group, 'new-group',
           'It should update the group ID in the view model when the focused ' +
           'group changes.');
       });