docs(ngIf): remove invalid comment from CSS

We cannot use valid /* ... */ CSS comments in examples because they break the parsing
of the ngdoc comments.  We can't use inline // comments because these are not valid in
CSS.

We could use the //!annotate extension to the ngdoc parser but this does not seem to be
working.  It is best to simply remove this line.

Closes #5234

src/ng/directive/ngIf.js

@@ -59,9 +59,6 @@
         padding:10px;
       }
 
-      /*
-        The transition styles can also be placed on the CSS base class above
-      */
       .animate-if.ng-enter, .animate-if.ng-leave {
         -webkit-transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;
         transition:all cubic-bezier(0.250, 0.460, 0.450, 0.940) 0.5s;