fix($animate): insert elements at the start of the parent container i…

…nstead of at the end

With 1.2.x, `$animate.enter` and `$animate.move` both insert the element at the end of the provided
parent container element when only the `parent` element is provided. If an `after` element is provided
then they will place the inserted element after that one. This works fine, but there is no way to
place an item at the top of the provided parent container using these two APIs.

With this change, if the `after` argument is not specified for either `$animate.enter` or `$animate.move`,
the new child element will be inserted into the first position of the parent container element.

Closes #4934
Closes #6275

BREAKING CHANGE: $animate will no longer default the after parameter to the last element of the parent
container. Instead, when after is not specified, the new element will be inserted as the first child of
the parent container.

To update existing code, change all instances of `$animate.enter()` or `$animate.move()` from:

`$animate.enter(element, parent);`

to:

`$animate.enter(element, parent, angular.element(parent[0].lastChild));`

src/ng/animate.js

@@ -111,8 +111,9 @@ var $AnimateProvider = ['$provide', function($provide) {
        * @ngdoc method
        * @name $animate#enter
        * @function
-       * @description Inserts the element into the DOM either after the `after` element or within
-       *   the `parent` element. Once complete, the done() callback will be fired (if provided).
+       * @description Inserts the element into the DOM either after the `after` element or
+       * as the first child within the `parent` element. Once complete, the done() callback
+       * will be fired (if provided).
        * @param {DOMElement} element the element which will be inserted into the DOM
        * @param {DOMElement} parent the parent element which will append the element as
        *   a child (if the after element is not present)
@@ -122,14 +123,9 @@ var $AnimateProvider = ['$provide', function($provide) {
        *   inserted into the DOM
        */
       enter : function(element, parent, after, done) {
-        if (after) {
-          after.after(element);
-        } else {
-          if (!parent || !parent[0]) {
-            parent = after.parent();
-          }
-          parent.append(element);
-        }
+        after
+            ? after.after(element)
+            : parent.prepend(element);
         async(done);
       },
 

test/ng/animateSpec.js

@@ -15,6 +15,19 @@ describe("$animate", function() {
       expect(element.contents().length).toBe(1);
     }));
 
+    it("should enter the element to the start of the parent container",
+      inject(function($animate, $compile, $rootScope) {
+
+      for(var i = 0; i < 5; i++) {
+        element.append(jqLite('<div> ' + i + '</div>'));
+      }
+
+      var child = jqLite('<div>first</div>');
+      $animate.enter(child, element);
+
+      expect(element.text()).toEqual('first 0 1 2 3 4');
+    }));
+
     it("should remove the element at the end of leave animation", inject(function($animate, $compile, $rootScope) {
       var child = $compile('<div></div>')($rootScope);
       element.append(child);