Allow to have several elements that use the same target

[B-Prod]

Currently it is not possible to have two elements that target the same canvas. In such case, only the first processed element may open the canvas, the other element is ignored.

Example code that fails:

<button class="offcanvas-toggle" data-toggle="offcanvas" data-target="#js-bootstrap-offcanvas-example">Click me</button>

<button class="offcanvas-toggle" data-toggle="offcanvas" data-target="#js-bootstrap-offcanvas-example">Click me too</button>

<div id="js-bootstrap-offcanvas-example">I am the offcanvas content</div>

The expected behaviour would be to have the canvas being opened by any buttons that have the correct target.