cl/375855105 Extract AMP Cache Domain validation, part 1 (ampproject#…

…34558)

Co-authored-by: honeybadgerdontcare <sedano@google.com>

validator/js/engine/htmlparser-interface.js

@@ -250,6 +250,15 @@ const ParsedHtmlTag = class {
  return !!this.extensionScriptNameAttribute_();
  }
 
+ /**
+ * Tests if this is an AMP Cache domain.
+ * @param {string} src
+ * @return {boolean}
+ */
+ isAmpCacheDomain_(src) {
+ return src.startsWith('https://cdn.ampproject.org');
+ }
+
  /**
  * Tests if this is an async script tag.
  * @return {boolean}
@@ -268,7 +277,7 @@ const ParsedHtmlTag = class {
  const src = this.getAttrValueOrNull_('src');
  if (src === null) return false;
  return this.isAsyncScriptTag_() && !this.isExtensionScript() &&
- src.startsWith('https://cdn.ampproject.org/') &&
+ this.isAmpCacheDomain_(src) &&
  (src.endsWith('/v0.js') || src.endsWith('/v0.mjs') ||
  src.endsWith('/v0.mjs?f=sxg'));
  }