data-toggle="button" initial active state #11535
Description
Using data-toggle="buttons" doesn't set the initial active state of the radio/checkbox buttons if they are already checked.
In the following example, the first button should get a class of active when the widget is initialized, but it does not.
<div class="btn-group" data-toggle="buttons">
<label class="btn btn-primary">
<input type="radio" name="options" id="option1" checked="checked"> Option 1
</label>
<label class="btn btn-primary">
<input type="radio" name="options" id="option2"> Option 2
</label>
<label class="btn btn-primary">
<input type="radio" name="options" id="option3"> Option 3
</label>
</div>