your angular version is different than the working plunker, updating the angular version will solve your problem
here is the DEMO
But note that this angular version is too old, and there is a separate angular module for animations in later versions,
with angular 1.4.x
here is a Example with latest way angular version.
include angular and angular-animate js files.
<script src="//ajax.googleapis.com/ajax/libs/angularjs/1.4.0-rc.2/angular.min.js"></script>
<script src="//ajax.googleapis.com/ajax/libs/angularjs/1.4.0-rc.2/angular-animate.js"></script>
and add the angular-animate dependency as,
var m = angular.module('App', ['ngAnimate']);
and use the css classes as,
.div.ng-enter {
opacity:0;
-webkit-transition-duration: 1000ms;
}
.div.ng-enter-active {
-webkit-transform:scale(1);
opacity:1;
}