Add support for new viewport-based units in isArbitraryLength

[dcastil]

New units are added to WebKit, so I should add them here as well.

E.g. lvh, svh, dvh, lvw, …

Sources:

• https://webkit.org/blog/12445/new-webkit-features-in-safari-15-4
• https://www.w3.org/TR/css-values-4/#viewport-variants
• https://caniuse.com/?search=dynamic%20viewport