de-bloating custom-elements by using Constructable Stylesheets

[pascalvos]

Describe the problem

Every time a custom element with styling is created it creates a <style> tag what also adds a dom element.
Custom elements already adds more dom elements so allowing to remove one that is mostly there always would realy make a big difference in dom node creation and also performance.

if any more information needed i can help :)

Describe the proposed solution

Solution is like LIT implementing usage of Constructable Stylesheets.
Constructable Stylesheets are implementend now in every browser.
svelte beeing all about performance this would be a great step in the right direction for custom element creation with svelte

preventing an excessive DOM size: https://developer.chrome.com/docs/lighthouse/performance/dom-size/
Information on Constructable Stylesheets: https://web.dev/constructable-stylesheets/ and https://github.com/WICG/construct-stylesheets/blob/main/explainer.md

Alternatives considered

not really

Importance

would make my life easier

[Portals]

Using constructable stylesheets would be a great improvement because the current solution of appending style tags will cause issues when a Content Security Policy is in place that disallows inline styles. In contrast, constructable stylesheets are not subject to Content Security Policy restrictions on inline styles.