Update to disallow @import rules

Author: mfreed7

cssom-1/Overview.bs

@@ -775,7 +775,7 @@ represents a style sheet as defined by the CSS specification. In the CSSOM a
   </dd>
 </dl>
 
-<a>CSS style sheet</a> has a number of associated state items:
+A <a>CSS style sheet</a> has a number of associated state items:
 
 <dl dfn-for="CSSStyleSheet">
  <dt><dfn id=concept-css-style-sheet-type>type</dfn>
@@ -994,8 +994,8 @@ The <dfn method for=CSSStyleSheet>insertRule(<var>rule</var>, <var>index</var>)<
  <li>If the <a>disallow modification flag</a> is set, throw a {{NotAllowedError}} {{DOMException}}.
  <li>Let <var>parsed rule</var> be the return value of invoking <a>parse a rule</a> with <var>rule</var>.
  <li>If <var>parsed rule</var> is a syntax error, return <var>parsed rule</var>.
- <li>If <var>parsed rule</var> is an <a>@import</a> rule, and the <a>constructed flag</a> or any ancestor
- style sheet's <a>constructed flag</a> is set, throw a {{NotAllowedError}} {{DOMException}}.
+ <li>If <var>parsed rule</var> is an <a>@import</a> rule, and the <a>constructed flag</a> is set, throw
+ a {{SyntaxError}} {{DOMException}}.
  <li>Return the result of invoking <a>insert a CSS rule</a> <var>rule</var> in the <a for=CSSStyleSheet>CSS rules</a>
  at <var>index</var>.
 </ol>
@@ -1017,36 +1017,14 @@ The <dfn method for=CSSStyleSheet>replace(<a for=CSSRule>text</a>)</dfn> method
  <li>Set the <a>disallow modification flag</a>.
  <li><a>In parallel</a>, do these steps:
  <ol>
-   <li>Let <var>rules</var> be the result of running <a>parse a list of rules</a> from <var>text</var>. If <var>rules</var> is not a list of rules
-   (i.e. an error occurred during parsing), set <var>rules</var> to an empty list.
-   <li>Wait for loading of <a>@import</a> rules in <var>rules|</var>and any nested <a>@import</a>s from those rules (and so on).
-   <ul>
-     <li>If any of them failed to load, <a>terminate</a> fetching of the remaining <a>@import</a> rules,  and <a>queue a task</a> on the
-     <a>networking task source</a> to perform the following steps:
-     <ol>
-       <li>Unset <var>sheet</var>'s <a>disallow modification flag</a>.
-       <li>Reject <var>promise</var> with a {{NetworkError}} {{DOMException}}.
-     </ol>
-     <li>Otherwise, once  all of them have finished loading, <a>queue a task</a> on the [<a>etworking task source</a> to perform the
-     following steps:
-     <ol>
-       <li>Set <var>sheet</var>'s <a>CSS rules</a> to <var>rules</var>.
-       <li>Unset <var>sheet</var>'s <a>disallow modification flag</a>.
-       <li>Resolve <var>promise</var> with <var>sheet</var>.
-     </ol>
-   </ul>
-    <p class="note">
-      Note: Loading  of <a>@import</a> rules should follow the rules used for fetching style sheets for <a>@import</a> rules of
-      stylesheets from &lt;link> elements, in regard to what counts as success, CSP, and Content-Type header checking.
-    </p>
-    <p class="note">
-      Note: We will use the <a>fetch group</a> of <var>sheet</var>'s <a>constructor document</a>'s <a>relevant settings object</a> for
-      <a>@import</a> rules and other (fonts, etc) loads.
-    </p>
-    <p class="note">
-      Note: The rules regarding loading mentioned above are currently not specified rigorously anywhere.
-    </p>
-   <li>Return <var>promise</var>.
+   <li>Let <var>rules</var> be the result of running <a>parse a list of rules</a> from <var>text</var>. If <var>rules</var> is
+   not a list of rules (i.e. an error occurred during parsing), set <var>rules</var> to an empty list.
+   <li>If <var>rules</var> contains one or more <a>@import</a> rules, <a lt="remove a CSS rule">remove those rules</a> from <var>rules</var>.
+   <li>Set <var>sheet</var>'s <a>CSS rules</a> to <var>rules</var>.
+   <li>Unset <var>sheet</var>'s <a>disallow modification flag</a>.
+   <li>Resolve <var>promise</var> with <var>sheet</var>.
+ </ol>
+ <li>Return <var>promise</var>.
 </ol>
 
 The <dfn method for=CSSStyleSheet>replaceSync(<a for=CSSRule>text</a>)</dfn> method must run the following steps:
@@ -1055,7 +1033,7 @@ The <dfn method for=CSSStyleSheet>replaceSync(<a for=CSSRule>text</a>)</dfn> met
  {{DOMException}}.
  <li>Let <var>rules</var> be the result of running <a>parse a list of rules</a> from <var>text</var>. If <var>rules</var> is
  not a list of rules (i.e. an error occurred during parsing), set <var>rules</var> to an empty list.
- <li>If <var>rules</var> contains one or more <a>@import</a> rules, throw a {{NotAllowedError}} {{DOMException}}.
+ <li>If <var>rules</var> contains one or more <a>@import</a> rules, <a lt="remove a CSS rule">remove those rules</a> from <var>rules</var>.
  <li>Set <a>CSS rules</a> to <var>rules</var>.
 </ol>