Pass shadow dom options down to SvelteElement

src/compile/render-dom/index.ts

@@ -445,11 +445,10 @@ export default function dom(
 		builder.add_block(deindent`
 			class ${name} extends @SvelteElement {
 				constructor(options) {
-					super();
+					super(${should_use_shadow_dom ? '' : '{ use_shadow_dom: true }'});
 
 					${css.code && should_use_shadow_dom && `this.shadowRoot.innerHTML = \`<style>${escape(css.code, { only_escape_at_symbol: true }).replace(/\\/g, '\\\\')}${options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
 
-					// TODO: Figure out what target should point to
 					@init(this, { target: this.shadowRoot }, ${definition}, create_fragment, ${not_equal}, ${prop_names});
 
 					${dev_props_check}

src/internal/Component.js

@@ -115,9 +115,9 @@ export function init(component, options, instance, create_fragment, not_equal, p
 export let SvelteElement;
 if (typeof HTMLElement !== 'undefined') {
 	SvelteElement = class extends HTMLElement {
-		constructor() {
+		constructor({ use_shadow_dom = true } = {}) {
 			super();
-			if (options.shadowDom !== false) {
+			if (use_shadow_dom) {
 				this.attachShadow({ mode: 'open' });
 			}
 		}