Remove getShadowRootDocument() again

This was used to create HTML elements for a shadow dom, but this
is now provided by the scoped-elements mixin via this.createScopedElement().

One way to handle this is enough, so remove this again.
All users have been ported already.

packages/common/src/utils.js

@@ -14,24 +14,4 @@ export const combineURLs = (baseURL, addedURL) => {
         baseURL += '/';
     }
     return new URL(addedURL.replace(/^\/+/, ''), baseURL).href;
-};
-
+};
\ No newline at end of file
-/**
- * Returns a Document like thing that can be used to create elements.
- *
- * It provides createElement()/createElementNS()/importNode().
- * The Document type annotation, while not correct, is used here for simplicity.
- *
- * https://github.com/WICG/webcomponents/blob/gh-pages/proposals/Scoped-Custom-Element-Registries.md#scoped-element-creation-apis
- *
- * @param {HTMLElement} element
- * @returns {Document|null}
- */
-export function getShadowRootDocument(element) {
-    // In case the polyfill is loaded return the shadowRoot
-    // otherwise fall back to the global document
-    if (ShadowRoot.prototype.createElement !== undefined) {
-        return element.shadowRoot;
-    }
-    return document;
-}

packages/common/test/unit.js

 import {expect, assert} from '@esm-bundle/chai';
 import * as utils from '../utils';
 import * as styles from '../styles';
-import {combineURLs, getShadowRootDocument} from '../';
+import {combineURLs} from '../';
 import '../jsonld.js';
 
 suite('utils', () => {
@@ -34,16 +34,6 @@ suite('utils', () => {
         assert.isTrue(res);
     });
 
-    test('getShadowRootDocument', () => {
-        class SomeElement3 extends HTMLElement {}
-        let res = utils.defineCustomElement('test-some-element-3', SomeElement3);
-        assert.isTrue(res);
-        let elm = new SomeElement3();
-        elm.attachShadow({mode: 'open'});
-        let doc = getShadowRootDocument(elm);
-        assert.isFunction(doc.createElement);
-    });
-
     test('getAssetURL', () => {
         // Backwards compat
         assert.equal(new URL(utils.getAssetURL('foo/bar')).pathname, '/foo/bar');