fix: certain articles not correctly identified as having platform specific content (#22887)

Author: mikesurowiec

lib/page.js

@@ -250,18 +250,16 @@ class Page {
       })
     }
 
-    // set a flag so layout knows whether to render a mac/windows/linux switcher element
-    this.includesPlatformSpecificContent =
-      html.includes('extended-markdown mac') ||
-      html.includes('extended-markdown windows') ||
-      html.includes('extended-markdown linux')
-
     this.detectedPlatforms = [
-      html.includes('extended-markdown mac') && 'mac',
-      html.includes('extended-markdown windows') && 'windows',
-      html.includes('extended-markdown linux') && 'linux',
+      (html.includes('extended-markdown mac') || html.includes('platform-mac')) && 'mac',
+      (html.includes('extended-markdown windows') || html.includes('platform-windows')) &&
+        'windows',
+      (html.includes('extended-markdown linux') || html.includes('platform-linux')) && 'linux',
     ].filter(Boolean)
 
+    // set a flag so layout knows whether to render a mac/windows/linux switcher element
+    this.includesPlatformSpecificContent = this.detectedPlatforms.length > 0
+
     return html
   }