fix(playground): preserve HTML comments (#11304)

Problem: Comments were discarded when running an example in the Playground.

Solution: Clone comments as well, instead of discarding them.

client/public/runner.html

@@ -62,10 +62,14 @@
           parent.innerHTML = html;
         } else {
           for (const child of dummy.childNodes) {
-            if (child.nodeType == Node.TEXT_NODE) {
+            if (child.nodeType === Node.TEXT_NODE) {
               parent.appendChild(document.createTextNode(child.textContent));
               continue;
             }
+            if (child.nodeType === Node.COMMENT_NODE) {
+              parent.appendChild(document.createComment(child.data));
+              continue;
+            }
             if (child.nodeType !== Node.ELEMENT_NODE) {
               continue;
             }