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      <base href="https://bugs.webkit.org/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Cannot attach Shadow root to unregistered custom element name"
   href="https://bugs.webkit.org/show_bug.cgi?id=158550">158550</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Cannot attach Shadow root to unregistered custom element name
          </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>ericbidelman&#64;chromium.org
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>cdumez&#64;apple.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Repo:
1. Visit <a href="http://jsbin.com/kowodikoyo/edit?html,output">http://jsbin.com/kowodikoyo/edit?html,output</a> in Safari TP version 9.1.2 (11601.7.4, 11602.1.35), or Webkit Nightly Version 9.1.1 (11601.6.17, r201834)
2. Click the pink button. 

Expected:
A ripple animation where you click.

Actual:

Running the same demo (<a href="http://jsbin.com/kowodikoyo/edit?html,output">http://jsbin.com/kowodikoyo/edit?html,output</a>) in Chrome Canary 52.0.2762.0 works as expected. The ripple animation plays.

It appears that attachShadowRoot is not working with a viable custom element name. Changing better-button -&gt; div makes the demo work in Safari TP and WK Nightly.</pre>
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      <ul>
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