use target top-level origin

fetch.bs

@@ -2059,7 +2059,7 @@ given <var>request</var>, run these steps:
 <ol>
  <li><p>If <var>request</var> is a <a>navigation request</a>, set <var>topLevelOrigin</var>
  to <var>request</var>'s <a for=request>reserved client</a>'s
- <a for="environment">top-level origin</a>. Otherwise, if <var>environmentSettings</var> is
+ <a for="environment">target top-level origin</a>. Otherwise, if <var>environmentSettings</var> is
  null, return null, else, set <var>topLevelOrigin</var> to <var>environmentSettings</var>'s
  <a for="environment settings object">top-level origin</a>.