Remove fallback code for old browsers that don't support <template>

h/static/scripts/tests/util/dom-test.js

@@ -55,19 +55,11 @@ describe('util/dom', () => {
   });
 
   describe('cloneTemplate', () => {
-    it('clones the first child of the template when <template> is supported', () => {
+    it('clones the first child of the template', () => {
       const template = document.createElement('template');
       template.innerHTML = '<div id="child"></div>';
       const clone = domUtil.cloneTemplate(template);
       assert.deepEqual(clone.outerHTML, '<div id="child"></div>');
     });
-
-    it('clones the first child of the template when <template> is not supported', () => {
-      const template = createDOM(
-        '<fake-template><div id="child"></div></fake-template>',
-      );
-      const clone = domUtil.cloneTemplate(template);
-      assert.deepEqual(clone.outerHTML, '<div id="child"></div>');
-    });
   });
 });

h/static/scripts/util/dom.js

@@ -49,36 +49,12 @@ export function findRefs(el) {
   return map;
 }
 
-/**
- * Return the first child of `node` which is an `Element`.
- *
- * Work around certain browsers (IE, Edge) not supporting firstElementChild on
- * Document, DocumentFragment.
- *
- * @param {Node} node
- */
-function firstElementChild(node) {
-  for (let i = 0; i < node.childNodes.length; i++) {
-    if (node.childNodes[i].nodeType === Node.ELEMENT_NODE) {
-      return node.childNodes[i];
-    }
-  }
-  // istanbul ignore next
-  return null;
-}
-
 /**
  * Clone the content of a <template> element and return the first child Element.
  *
  * @param {HTMLTemplateElement} templateEl
  */
 export function cloneTemplate(templateEl) {
-  if (templateEl.content) {
-    // <template> supported natively.
-    const content = templateEl.content.cloneNode(true);
-    return firstElementChild(content);
-  } else {
-    // <template> not supported. Browser just treats it as an unknown Element.
-    return templateEl.firstElementChild.cloneNode(true);
-  }
+  const content = templateEl.content.cloneNode(true);
+  return content.firstElementChild;
 }