docs(ngShow): simplify the CSS transition code

The animation example contains unnecessarily complex CSS animation
code in it and the conventions are off.

Related #12631

Author: matsko

src/ng/directive/ngShowHide.js

@@ -125,9 +125,7 @@ var NG_HIDE_IN_PROGRESS_CLASS = 'ng-hide-animate';
         background: white;
       }
 
-      .animate-show.ng-hide-add.ng-hide-add-active,
-      .animate-show.ng-hide-remove.ng-hide-remove-active {
-        -webkit-transition: all linear 0.5s;
+      .animate-show.ng-hide-add, .animate-show.ng-hide-remove {
         transition: all linear 0.5s;
       }
 
@@ -284,7 +282,6 @@ var ngShowDirective = ['$animate', function($animate) {
     </file>
     <file name="animations.css">
       .animate-hide {
-        -webkit-transition: all linear 0.5s;
         transition: all linear 0.5s;
         line-height: 20px;
         opacity: 1;