Accordion: doesn't work in template with whitespaces

[wkeese]

When you have an accordion inside a template, there's an exception instantiating the widget. For example, in a template:

        <d-accordion>
            <d-panel label="Title one">
                ...
            </d-panel>
            <d-panel label="Title two">
                ...

The problem happens because when the template is compiled, it ends up with statements like:

accordion.appendChild(document.createTextNode("..."))

(or something like that), and Accordion (and perhaps other widgets) aren't set up to handle that.

onAddChild: dcl.superCall(function (sup) {
    return function (node) {
        var res = sup.call(this, node);
        this._panelList.push(this._setupUpgradedChild(node));
        this.notifyCurrentValue("_panelList");
        return res;
    };
}),

The text should be ignored, not registered as a panel.

The workaround is to remove spaces between the nodes, like this:

        <d-accordion class="list"
            ><d-panel label="Title one">
                ...
            </d-panel
            ><d-panel label="Title two">
                ...

[wkeese]

Probably delite/Container should be modified to only call onAddChild() for Elements, not for text nodes. Note that the spec for that method is confused in that it mentions both Element and Node as though they are identical.