JSM CDN use in stackoverflow sample

Newer thought to have JSM CDN useful in stackoverflow. If you check my answer, it is capable of running the sample inline from CDN.

   https://stackoverflow.com/questions/50404970/web-components-pass-data-to-and-from

Data from HTML attribute - Declarative Programming with Web Components

How to pass JSON string from HTML as object for data binding of Polymer Web Component?

The answer resides in embedding of data into URL of iron-ajax.

vaadin-elements-demo.html

<iron-ajax url='data:text/json;charset=utf-8, 
                [{"label": "Hydrogen", "value": "H"} 
                ,{"label": "Oxygen"  , "value": "O"} 
                ,{"label": "Carbon"  , "value": "C"} 
                ]'
           last-response="{{lifeElements}}" auto handle-as="json"></iron-ajax>
<vaadin-combo-box id="cbDemo"
        label="Label, value:[[cbDemoValue]]"
        placeholder="Placeholder"
        items="[[lifeElements]]"
        value="{{ cbDemoValue }}"
>
    <template>
        [[index]]: [[item.label]] <b>[[item.value]]</b>
    </template>
</vaadin-combo-box>
<vaadin-combo-box label="Disabled" disabled value="H" items="[[lifeElements]]"></vaadin-combo-box>
<vaadin-combo-box label="Read-only" readonly value="O" items="[[lifeElements]]"></vaadin-combo-box>