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      <base href="https://bugs.webkit.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - importNode from template doesn't instantiate custom element"
   href="https://bugs.webkit.org/show_bug.cgi?id=163147">163147</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>importNode from template doesn't instantiate custom element
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>Safari Technology Preview
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>HTML DOM
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>jan&#64;component.kitchen
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>cdumez&#64;apple.com
          </td>
        </tr></table>
      <p>
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        <pre>See <a href="http://jsbin.com/tukocup/1/edit?html,console">http://jsbin.com/tukocup/1/edit?html,console</a>.

    class TestElement extends HTMLElement {}
    customElements.define('test-element', TestElement);

    let template = document.createElement('template');
    template.innerHTML = `&lt;test-element&gt;&lt;/test-element&gt;`;
    let clone = document.importNode(template.content, true);
    let element = clone.querySelector('test-element');
    console.log(element instanceof TestElement); // true in Chrome Canary, false in WebKit

This defines a custom element, then tries to use it in a template. Following the importNode call, the test-element node should be an instance of TestElement, but it's not. (It works as expected in Chrome Canary.)</pre>
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