Polymer 纸张下拉菜单和核心下拉覆盖错误

我试图在自定义聚合元素中包含一个纸张下拉菜单元素，我发现以下错误：

Uncaught NotSupportedError: Failed to execute 'animate' on 'Element': Partial keyframes are not supported.
animation-constructor.js:61 Uncaught NotSupportedError: Failed to execute 'animate' on 'Element': Partial keyframes are not supported.
animation-constructor.js:61 Uncaught NotSupportedError: Failed to execute 'animate' on 'Element': Partial keyframes are not supported.

还有这个警告：

core-dropdown-overlay: dropdown's offsetParent must be the relatedTarget or the relatedTarget's offsetParent!

纸张下拉菜单显示良好，单击时会出现这些错误/警告。代码嵌入到页面本身时工作正常

我的页面结构如下：

<page-form>
  ...
  <subform-element></subform-element>
  ...
</page-form>

...
...

PageForm是另一个表示我的页面的聚合元素，subform元素是包含纸张下拉菜单的表单的一部分

<polymer-element name="subform-element" noscript>
    <template>
        <link rel="stylesheet" href="subform-element.css">
        <div layout horizontal center>
            <paper-dropdown-menu label="Disease" layered flex>
                <paper-dropdown class="dropdown core-transition core-closed">
                    <core-menu class="menu">
                        <paper-item tabindex="0">Foulbrood</paper-item>
                        <paper-item tabindex="0">Varroa</paper-item>
                        <paper-item tabindex="0">Tracheal Mites</paper-item>
                        <paper-item tabindex="0">Other</paper-item>
                    </core-menu>
                </paper-dropdown>
            </paper-dropdown-menu>
            <paper-input-decorator label="disease notes" floatinglabel="disease notes" flex>
                <input is="core-input" placeholder="disease notes">
            </paper-input-decorator>
        </div>
    </template>
</polymer-element>

福尔布罗德
瓦罗亚
气管螨
其他

我看到了聚合物版本0.5.5和Chrome41中的错误