Make text visible when font loading takes longer than 3 seconds

LayoutTests/http/tests/webfont/slow-ahem-loading.cgi

 #!/usr/bin/perl -wT
+use CGI;
+use Time::HiRes;
+
+my $cgi = new CGI;
+my $delay = $cgi->param('delay');
+$delay = 1000 unless $delay;
 
 print "Content-type: application/octet-stream\n";
 print "Cache-control: no-cache, no-store\n\n";
-sleep(1);
+Time::HiRes::sleep($delay / 1000);
 open FH, "<../../../resources/Ahem.ttf" or die;
 while (<FH>) { print; }
 close FH;