Fix null URL blob handling in "get an element's noopener"

Similar to 54828a7.

Author: shannonbooth

source

@@ -25575,8 +25575,8 @@ document.body.appendChild(wbr);</code></pre>
    true.</p></li>
 
    <li>
-    <p>If <var>url</var>'s <span data-x="concept-url-scheme">scheme</span> is "<code
-    data-x="">blob</code>":</p>
+    <p>If <var>url</var>'s <span data-x="concept-url-blob-entry">blob URL entry</span> is not
+    null:</p>
 
     <ol>
      <li><p>Let <var>blobOrigin</var> be <var>url</var>'s <span