fix: change tabindex from 0 to -1 when focusing first item

test/vaadin-list-mixin.html

@@ -307,6 +307,14 @@
           list.focus();
           expect(spy.calledOnce).to.be.true;
         });
+
+        it('should change tabindex from -1 to 0 on first non-disabled item when focusing it', () => {
+          list.items.forEach((item) => {
+            item.tabIndex = -1;
+          });
+          list.focus();
+          [-1, -1, 0, -1].forEach((val, idx) => expect(list.items[idx].tabIndex).to.equal(val));
+        });
       });
 
       describe('tabIndex when all the items are disabled', () => {

vaadin-list-mixin.html

@@ -294,7 +294,7 @@
       } else if (this.items) {
         const idx = this._getAvailableIndex(0, null, item => !item.disabled);
         if (idx >= 0) {
-          this.items[idx].focus();
+          this._focus(idx);
         }
       }
     }