Add <script> and <noscript> elements

[petele]

Split <script> and <noscript> into separate elements as they do very different things.
Used compute_from: html.elements.script since supports_static is not baseline.

[foolip]

Since <noscript> only makes sense to use together with <script> (as a fallback) I think we should merge these into just <script>, and maybe mention <noscript> briefly in the description.

[petele]

@foolip - done. Did not mention noscript in description, but added to the name.