Add inline style hack fallback (fixes Safari)

This patch provides an alternate patch for animated inline styles.
If replacing element.style with an AnimatedCSSStyleDeclaration is not allowed (which is the case for Safari) it will instead patch the existing inline style object methods to behave in a similar way.
Property getters and setters are not patched and will not function normally while under animation with this fallback.
This patch depends on https://github.com/web-animations/web-animations-js/pull/495 landing first.