Bug 1729640 - P8. Request longer timeout for browser_web_process_isol…

…ation test. r=farre

Open the test tab takes some time in this testcase
(https://searchfox.org/mozilla-central/rev/d2f8488b6a704443a5c5bfc6d2878171b5f0d393/dom/ipc/tests/browser_web_process_isolation.js#31-43)
, and we open the tab multiple times in this testcase.

Since we add 2 more test scenarios for the testcase, this testcase need more time to finish.

Differential Revision: https://phabricator.services.mozilla.com/D130478

dom/ipc/tests/browser_web_process_isolation.js

@@ -5,6 +5,8 @@ ok(
   "this test requires fission to function!"
 );
 
+requestLongerTimeout(3);
+
 const WebContentIsolationStrategy = {
   IsolateNothing: 0,
   IsolateEverything: 1,