Tabs: set first visible tab as active if not active set

[nilsburg]

What steps will reproduce the problem?

echo \yii\bootstrap\Tabs::widget([
        'items'=>[
            [
                'label'       => 'Tab 1',
                'content'     => 'some content',
                'visible'     => false
            ],
            [
                'label'       => 'Tab 2',
                'content'     => 'some content',
                'visible'     => true
            ],
            [
                'label'       => 'Tab 3',
                'content'     => 'some content',
                'visible'     => true
            ],
        ]
    ]);

What's expected?

Tab 2 should be active

What do you get instead?

No active tab.
I am not sure if this is on purpose, but I think that if no active tab is set, the first visible tab should be active.

Additional info

Q	A
Yii vesion	2.0.11.2
PHP version	5.6
Operating system	Ubuntu 16.04

[cebe]

fixed by #187