Add a no-shadow-dom acceptance test

test/custom-elements/index.js

@@ -81,7 +81,7 @@ describe('custom-elements', function() {
 							if (id.endsWith('.svelte')) {
 								const compiled = svelte.compile(code, {
 									customElement: true,
-									dev: config.dev
+									...config
 								});
 
 								return compiled.js;

test/custom-elements/samples/no-shadow-dom/_config.js

@@ -0,0 +1,4 @@
+export default {
+	customElement: true,
+	shadowDom: false
+};

test/custom-elements/samples/no-shadow-dom/main.svelte

@@ -0,0 +1,9 @@
+<svelte:options tag="custom-element"/>
+
+<h1>Hello world!</h1>
+
+<style>
+h1 {
+  color: blue;
+}
+</style>

test/custom-elements/samples/no-shadow-dom/test.js

@@ -0,0 +1,17 @@
+import * as assert from 'assert';
+import CustomElement from './main.svelte';
+
+export default function (target) {
+	new CustomElement({
+		target
+	});
+
+	assert.equal(target.innerHTML, '<custom-element><h1 class="svelte-619mm8">Hello world!</h1></custom-element>');
+
+	const el = target.querySelector('custom-element');
+	const h1 = el.querySelector('h1');
+	const { color } = getComputedStyle(h1);
+
+	assert.equal(h1.textContent, 'Hello world!');
+	assert.equal(color, 'rgb(0, 0, 255)');
+}