Dont send preload links headers if streaming

Co-authored-by: John Crepezzi <[email protected]>

Author: jhawthorn

actionview/lib/action_view/helpers/asset_tag_helper.rb

@@ -544,6 +544,7 @@ def resolve_link_as(extname, mime_type)
         MAX_HEADER_SIZE = 8_000 # Some HTTP client and proxies have a 8kiB header limit
         def send_preload_links_header(preload_links, max_header_size: MAX_HEADER_SIZE)
           return if preload_links.empty?
+          return if response.sending?
 
           if respond_to?(:request) && request
             request.send_early_hints("Link" => preload_links.join("\n"))

actionview/test/template/asset_tag_helper_test.rb

@@ -24,6 +24,7 @@ class FakeResponse
     def headers
       @headers ||= {}
     end
+    def sending?; false; end
   end
 
   def setup