fix(ngAnimate): fix cancelChildAnimations throwing exception

fix ngAnimate throwing exception in cancelChildAnimations on deletion of
element (ngAnimate's leave decorator) of repeated element when using
ng-include on this element.

Closes #4548
fix(ngdocs): remove the side search bar

BREAKING CHANGE

The side search bar on the docs page has been removed in favor of the
top search bar.
feat(ngdocs): add forward slash shortcut key for search bar