HTML Imports: Fix yet another FOUC

LayoutTests/http/tests/ManualTests/fouc/resources/slow-green.cgi

Index: LayoutTests/http/tests/ManualTests/fouc/resources/slow-green.cgi
diff --git a/LayoutTests/http/tests/htmlimports/resources/blocking-script-js.cgi b/LayoutTests/http/tests/ManualTests/fouc/resources/slow-green.cgi
similarity index 66%
copy from LayoutTests/http/tests/htmlimports/resources/blocking-script-js.cgi
copy to LayoutTests/http/tests/ManualTests/fouc/resources/slow-green.cgi
index f9746cc808f0c99122679cdc29ec536054664a91..90ba615727b635e18ea621507efacec79a004ba1 100755
--- a/LayoutTests/http/tests/htmlimports/resources/blocking-script-js.cgi
+++ b/LayoutTests/http/tests/ManualTests/fouc/resources/slow-green.cgi
@@ -1,10 +1,14 @@
 #!/usr/bin/perl -wT
 use strict;
 
-print "Content-Type: text/javascript\n\n";
+print "Content-Type: text/html\n\n";
 # If you want to make things super predictable, this will help for the cost of slowness.
 # In practice, CGI invocation overhead is sufficiently slow.
-# sleep 1;
+sleep 1;
 print <<EOF
-blockingScriptHasRun = true;
+<style>
+  #test {
+    background: green;
+  }
+</style>
 EOF