HTML Reporter: Faster "Hide passed" toggling on large test suites

Optimize the hidepassed click handler for large test suites by
avoiding internal function call overhead for the iterator, as well
as copying cost for the array. Shaves off ~100ms milliseconds on the
q4000 demo 1.65s to 1.5s (Chrome, CPU throttle 6x), and seems to defer
some unattributed costs to outside the critical path.

Cherry-picked from a729421 (3.0.0-dev).

src/html-reporter/html.js

@@ -196,10 +196,9 @@ const stats = {
       config[field.name] = value || false;
       let tests = id('qunit-tests');
       if (tests) {
-        const length = tests.children.length;
-        const children = tests.children;
-
         if (field.checked) {
+          const length = tests.children.length;
+          const children = tests.children;
           for (let i = 0; i < length; i++) {
             const test = children[i];
             const className = test ? test.className : '';
@@ -211,13 +210,18 @@ const stats = {
             }
           }
 
-          for (const hiddenTest of hiddenTests) {
-            tests.removeChild(hiddenTest);
+          // Optimization: Avoid `for-of` iterator overhead.
+          for (let i = 0; i < hiddenTests.length; i++) {
+            tests.removeChild(hiddenTests[i]);
           }
         } else {
-          while (hiddenTests.length) {
-            tests.appendChild(hiddenTests.shift());
+          // Optimization: Avoid `while (arr.length) arr.shift()` which would mutate the array many times.
+          // As of Chrome 126, HTMLElement.append(...hiddenTests) is still slower than
+          // calling appendChild in a loop.
+          for (let i = 0; i < hiddenTests.length; i++) {
+            tests.appendChild(hiddenTests[i]);
           }
+          hiddenTests.length = 0;
         }
       }
       window.history.replaceState(null, '', updatedUrl);