feat: trusted-types CSP compatibility for Web Components (#8135)

Author: fallaciousreasoning

src/compiler/compile/render_dom/index.ts

@@ -531,7 +531,10 @@ export default function dom(
 				constructor(options) {
 					super();
 
-					${css.code && b`this.shadowRoot.innerHTML = \`<style>${css.code.replace(regex_backslashes, '\\\\')}${css_sourcemap_enabled && options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
+					${css.code && b`
+						const style = document.createElement('style');
+						style.textContent = \`${css.code.replace(regex_backslashes, '\\\\')}${css_sourcemap_enabled && options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}\`
+						this.shadowRoot.appendChild(style)`}
 
 					@init(this, { target: this.shadowRoot, props: ${init_props}, customElement: true }, ${definition}, ${has_create_fragment ? 'create_fragment' : 'null'}, ${not_equal}, ${prop_indexes}, null, ${dirty});
 

test/js/samples/css-shadow-dom-keyframes/expected.js

@@ -34,7 +34,9 @@ function create_fragment(ctx) {
 class Component extends SvelteElement {
 	constructor(options) {
 		super();
-		this.shadowRoot.innerHTML = `<style>div{animation:foo 1s}@keyframes foo{0%{opacity:0}100%{opacity:1}}</style>`;
+		const style = document.createElement('style');
+		style.textContent = `div{animation:foo 1s}@keyframes foo{0%{opacity:0}100%{opacity:1}}`;
+		this.shadowRoot.appendChild(style);
 
 		init(
 			this,