fix($animate): don't break on anchored animations without duration

If the `from` element of an animation does not actually have an animation
then there will be no animation runner on that element. This is possible
if the element has the `ng-animate-ref` attribute but does not have any
CSS animations or transitions defined.

In this case, it is not necessary to try to update the host of the
non-existent runner.

Fixes #14641
Closes #14645

src/ngAnimate/animation.js

@@ -378,7 +378,8 @@ var $$AnimationProvider = ['$animateProvider', function($animateProvider) {
         }
 
         function update(element) {
-          getRunner(element).setHost(newRunner);
+          var runner = getRunner(element);
+          if (runner) runner.setHost(newRunner);
         }
       }
 

test/ngAnimate/animateCssSpec.js

@@ -1879,6 +1879,24 @@ describe("ngAnimate $animateCss", function() {
         expect(element).not.toHaveClass('ng-leave-active');
         expect(element).not.toHaveClass('ng-move-active');
       }));
+
+      it('should not break when running anchored animations without duration',
+        inject(function($animate, $document, $rootElement) {
+          var element1 = jqLite('<div class="item" ng-animate-ref="test">Item 1</div>');
+          var element2 = jqLite('<div class="item" ng-animate-ref="test">Item 2</div>');
+
+          jqLite($document[0].body).append($rootElement);
+          $rootElement.append(element1);
+
+          expect($rootElement.text()).toBe('Item 1');
+
+          $animate.leave(element1);
+          $animate.enter(element2, $rootElement);
+          $animate.flush();
+
+          expect($rootElement.text()).toBe('Item 2');
+        })
+      );
     });
 
     describe("class-based animations", function() {

test/ngAnimate/animateSpec.js

@@ -13,7 +13,7 @@ describe("animations", function() {
     };
   }));
 
-  afterEach(inject(function($$jqLite) {
+  afterEach(inject(function() {
     dealoc(element);
   }));