[scroll-animations] Include view-timeline properties in ComputedStyle diff

[chromium-wpt-export-bot]

This is required for the style recalc machinery to understand that changes in view-timeline properties may affect descendants and subsequent siblings. This problem was already solved for scroll-timeline, so it's a simple matter of also including view-timeline properties in the same place.

Bug: 1317765 Change-Id: I93af47ac4b2ef6714edbbe0e8b6ce9f002c72485 Reviewed-on: https://chromium-review.googlesource.com/3898994 WPT-Export-Revision: 9ef9cd76a57f7d52c27602782cf618eb62c58463