Minor refactoring

@import never invalidates any other following rule so it can be removed after
parsing all rules instead of immediately after parsing @import.

Author: cdoublev

lib/cssom/CSSStyleSheet-impl.js

@@ -1,6 +1,7 @@
 
 import { ACCESS_THIRD_PARTY_STYLESHEET_ERROR, UPDATE_LOCKED_STYLESHEET_ERROR, create as error } from '../error.js'
 import { insertCSSRule, parseCSSGrammar, parseStyleSheet, removeCSSRule } from '../parse/parser.js'
+import CSSImportRule from './CSSImportRule.js'
 import CSSRuleList from './CSSRuleList.js'
 import MediaList from './MediaList.js'
 import StyleSheetImpl from './StyleSheet-impl.js'
@@ -83,7 +84,7 @@ export default class CSSStyleSheetImpl extends StyleSheetImpl {
             this._document = null
             this._location = location
             this._originClean = originClean
-            this._rules = parseStyleSheet(rules, this, true)
+            this._rules = parseStyleSheet(rules, this)
             this.disabled = disabled
             this.media = createMediaList(media, globalObject)
             this.ownerNode = ownerNode
@@ -147,7 +148,7 @@ export default class CSSStyleSheetImpl extends StyleSheetImpl {
         this._disallowModification = true
         await Promise.resolve()
         this._rules.splice(0)
-        const rules = parseStyleSheet(text, this)
+        const rules = parseStyleSheet(text, this).filter(rule => !CSSImportRule.isImpl(rule))
         this._rules.push(...rules)
         this._disallowModification = false
         return wrapperForImpl(this)
@@ -162,7 +163,7 @@ export default class CSSStyleSheetImpl extends StyleSheetImpl {
             throw error(UPDATE_LOCKED_STYLESHEET_ERROR)
         }
         this._rules.splice(0)
-        const rules = parseStyleSheet(text, this)
+        const rules = parseStyleSheet(text, this).filter(rule => !CSSImportRule.isImpl(rule))
         this._rules.push(...rules)
     }
 }

lib/parse/parser.js

@@ -746,14 +746,13 @@ function consumeBlockContents(tokens, context, ignoreCloseCurlyBlock) {
 /**
  * @param {Stream} tokens
  * @param {object} context
- * @param {boolean} [allowImport]
  * @returns {CSSRuleImpl[]}
  * @see {@link https://drafts.csswg.org/css-syntax-3/#consume-a-stylesheets-contents}
  *
  * It deviates from the specification by validating and/or discarding rules here
- * instead of in consumeAtRule() or CSSStyleSheet.replace*().
+ * instead of in consumeAtRule().
  */
-function consumeStyleSheet(tokens, context, allowImport) {
+function consumeStyleSheet(tokens, context) {
     const rules = []
     while (!tokens.atEnd()) {
         if (tokens.consume(token => isDelimiter([' ', '<!--', '-->'], token))) {
@@ -763,7 +762,6 @@ function consumeStyleSheet(tokens, context, allowImport) {
             const rule = consumeAtRule(tokens, context)
             if (
                 isError(rule)
-                || (!allowImport && CSSImportRule.isImpl(rule))
                 || isInvalidIndexForRule(rules, rule, rules.length)
                 || isInvalidNamespaceRule(rules, rule)
             ) {
@@ -919,12 +917,11 @@ function parseBlockContents(input, context) {
 /**
  * @param {ReadableStream|Stream|string|object[]} input
  * @param {CSSStyleSheetImpl} context
- * @param {boolean} [allowImport]
  * @returns {CSSRuleImpl[]}
  * @see {@link https://drafts.csswg.org/css-syntax-3/#parse-a-stylesheet}
  */
-function parseStyleSheet(input, context, allowImport = false) {
-    return consumeStyleSheet(normalizeIntoTokens(input), createContext(context), allowImport)
+function parseStyleSheet(input, context) {
+    return consumeStyleSheet(normalizeIntoTokens(input), createContext(context))
 }
 
 /**