A clonable shadow tree is cloned in its entirety

Tests: web-platform-tests/wpt#44247.

Fixes #1249.

Author: annevk

dom.bs

@@ -4517,11 +4517,10 @@ dom-Range-extractContents, dom-Range-cloneContents -->
    <li><p>Set <var>copy</var>'s <a for=Element>shadow root</a>'s <a for=ShadowRoot>declarative</a>
    to <var>node</var>'s <a for=Element>shadow root</a>'s <a for=ShadowRoot>declarative</a>.
 
-   <li><p>If the <i>clone children flag</i> is set, then for each <a for=tree>child</a>
-   <var>child</var> of <var>node</var>'s <a for=Element>shadow root</a>, in <a>tree order</a>:
-   <a>append</a> the result of <a lt="clone a node">cloning</a> <var>child</var> with
-   <var>document</var> and the <i>clone children flag</i> set, to <var>copy</var>'s
-   <a for=Element>shadow root</a>.
+   <li><p>For each <a for=tree>child</a> <var>child</var> of <var>node</var>'s
+   <a for=Element>shadow root</a>, in <a>tree order</a>: <a>append</a> the result of
+   <a lt="clone a node">cloning</a> <var>child</var> with <var>document</var> and the
+   <i>clone children flag</i> set, to <var>copy</var>'s <a for=Element>shadow root</a>.
   </ol>
 
  <li><p>Return <var>copy</var>.