core-list not showing

http://stackoverflow.com/questions/27648328/why-polymer-core-list-doesnt-working

by kreide

HTML

<link rel="import" href="http://www.polymer-project.org/0.5/components/polymer/polymer.html">
<link rel="import" href="http://www.polymer-project.org/0.5/components/paper-elements/paper-elements.html">
<link rel="import" href="http://www.polymer-project.org/0.5/components/core-elements/core-elements.html">
<polymer-element name="my-el">
    <template>
        <style>
            core-list {
                height: 100%;
            }
            .item {
                box-sizing: border-box;
                height: 80px;
                border-bottom: 1px solid #ddd;
                padding: 4px;
                cursor: default;
                background-color: white;
                overflow: hidden;
            }
        </style>
        <div fit style="overflow:auto;">
             <h1>адfа</h1>
            <core-list data="{{ apartments }}">
                <template>
                    <div class="item">{{ model.text }}</div>
                </template>
            </core-list>
        </div>
    </template>
    <script>
        Polymer('my-el', {
            apartments: [],
            ready: function() {
                console.log('ready');
                this.apartments = [{
                    text: "lslslsls"
                }, {
                    text: "lslslsls2"
                }]
            }
        })
    </script>
</polymer-element>
    <my-el></my-el>