[BroadcastChannel] Use long timeout for opaque-origin tests

I haven't been able to confirm that this addresses the flakiness
with these tests, but the data URL worker tests do a similar amount
of work to the cross-partition tests which do seem to need the long
timeout.

Bug: 1322297
Change-Id: I585b24fd884fd135edc163cad77ea8ee56f11e9d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3668704
Reviewed-by: Ben Kelly <wanderview@chromium.org>
Commit-Queue: Andrew Williams <awillia@google.com>
Cr-Commit-Position: refs/heads/main@{#1007483}
diff --git a/webmessaging/broadcastchannel/opaque-origin.html b/webmessaging/broadcastchannel/opaque-origin.html
index c176229..1d05a90 100644
--- a/webmessaging/broadcastchannel/opaque-origin.html
+++ b/webmessaging/broadcastchannel/opaque-origin.html
@@ -2,6 +2,7 @@
 <html>
 <head>
 <meta charset=utf-8>
+<meta name="timeout" content="long">
 <title></title>
 <script src=/resources/testharness.js></script>
 <script src=/resources/testharnessreport.js></script>