move ES6 feature detection from home1.css to home1.js

Combine the two inline script blocks into a single try/catch
using new Function() so old browsers fail gracefully.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

groups/home/bootstrap5/home1.css

@@ -608,43 +608,6 @@
   });
 </script>
 
-<!-- If browser is pre-ES6, show a warning-->
-<script>
-  window.isES6 = false;
-</script>
-<script>
-  <!-- test ES6 functionality -->
-  // Arrow functions support
-  () => {};
-
-  // Class support
-  class __ES6FeatureDetectionTest {}
-
-  // Object initializer property and method shorthands
-  let es6a = true;
-  let es6b = {
-    es6a,
-    es6c() {
-      return true;
-    },
-    es6d: [1, 2, 3],
-  };
-
-  // Object destructuring
-  let { es6c, es6d } = es6b;
-
-  // Spread operator
-  let es6e = [...es6d, 4];
-
-  // ternary operator
-  let es6f = es6a ? "ternary" : "no ternary";
-
-  // nullish coalescing
-  es6a ??= 10;
-
-  window.isES6 = true;
-</script>
-
 <script type="text/javascript">
   window.onload = function () {
     <!-- display the error message if feature detection flags old browser -->