use script's baseurl for cssstylesheets

Author: keithamus

source

@@ -110277,8 +110277,12 @@ document.querySelector("button").addEventListener("click", bound);
    <li><p>Set <var>script</var>'s <span data-x="concept-script-parse-error">parse error</span> and
    <span data-x="concept-script-error-to-rethrow">error to rethrow</span> to null.</p></li>
 
+   <li><p>Let <var>baseUrl</var> be <var>script</var>'s <span data-x="concept-script-base-url">base
+   URL</span>.
+
    <li><p>Let <var>sheet</var> be the result of running the steps to <span>create a constructed
-   <code>CSSStyleSheet</code></span> with an empty dictionary as the argument.</p></li>
+   <code>CSSStyleSheet</code></span> with a dictionary with the following dictionary members:
+   «[ "<code data-x="">baseUrl</code>" → <var>baseUrl</var> ]»</p></li>
 
    <li>
     <p>Run the steps to <span>synchronously replace the rules of a <code>CSSStyleSheet</code></span>