Fix createElementFromAttrs bug (#31751)

The "false" value was not handled correctly, it would cause bugs in the
future (fortunately, this behavior is not used in code yet).

web_src/js/utils/dom.test.ts

@@ -10,7 +10,9 @@ test('createElementFromAttrs', () => {
     class: 'cls-1 cls-2',
     'data-foo': 'the-data',
     disabled: true,
+    checked: false,
     required: null,
+    tabindex: 0,
   });
-  expect(el.outerHTML).toEqual('<button id="the-id" class="cls-1 cls-2" data-foo="the-data" disabled=""></button>');
+  expect(el.outerHTML).toEqual('<button id="the-id" class="cls-1 cls-2" data-foo="the-data" disabled="" tabindex="0"></button>');
 });