fix($animate): cancel any ongoing child animations during move and leave animations
refactor($animate): queue all successive animations to use only one reflow
fix($animate): ensure structural animations skip all child animations even if no animation is present during compile

Closes #3215
chore(ngdocs): improve the side search animation effects
fix($animate): perform internal caching on getComputedStyle to boost the performance of CSS3 transitions/animations

Closes #4011
Closes #4124