This patch removes the need to include the Web Animations API Polyfill
(web-animations-js) as a dependency. Angular will now fallback to using
CSS Keyframes in the event that `element.animate` is no longer supported
by the browser.
In the event that an application does use `AnimationBuilder` then the
web-animations-js polyfill is required to enable programmatic,
position-based access to an animation.
Closes#17496
PR Close#22143
Add enough BUILD files to make it possible to
`bazel build packages/core/test`
Also re-format BUILD.bazel files with Buildifier.
Add a CI lint check that they stay formatted.
PR Close#20768
Matias Niemelä
Misko Hevery
Alex Eagle
Tobias Bosch