[Blazor] Always treat "preloads" as new elements when doing enhanced navigation (#63239)

Author: maraf

src/Components/Web.JS/src/Rendering/DomMerging/DomSync.ts

@@ -308,6 +308,11 @@ function domNodeComparer(a: Node, b: Node): UpdateCost {
         return UpdateCost.Infinite;
       }
 
+      // Always treat "preloads" as new elements.
+      if (isPreloadElement(a as Element) || isPreloadElement(b as Element)) {
+        return UpdateCost.Infinite;
+      }
+
       return UpdateCost.None;
     case Node.DOCUMENT_TYPE_NODE:
       // It's invalid to insert or delete doctype, and we have no use case for doing that. So just skip such
@@ -319,6 +324,10 @@ function domNodeComparer(a: Node, b: Node): UpdateCost {
   }
 }
 
+function isPreloadElement(el: Element): boolean {
+  return el.tagName === 'LINK' && el.attributes.getNamedItem('rel')?.value === 'preload';
+}
+
 function upgradeComponentCommentsToLogicalRootComments(root: Node): ComponentDescriptor[] {
   const serverDescriptors = discoverComponents(root, 'server') as ServerComponentDescriptor[];
   const webAssemblyDescriptors = discoverComponents(root, 'webassembly') as WebAssemblyComponentDescriptor[];