Bug 1483444: Skip browser_startup_content in verify mode. r=Felipe DONTBUILD

Verify mode runs tests multiple times. In the case of browser_startup_content.js,
this gives extra modules a chance to load before subsequent runs, which leads
to failures.

Since there's no particular reason to run this test in verify mode, the
obvious solution is to just disable it.

Differential Revision: https://phabricator.services.mozilla.com/D3430

--HG--
extra : rebase_source : 034fc518bc3e4346cc99404def659b7cf3233308
extra : amend_source : d80dfffefbc674a24c118800af03a12f638fb3a6

browser/base/content/test/performance/browser.ini

@@ -18,7 +18,7 @@ skip-if = asan || debug || (os == 'win' && bits == 32) # Bug 1382809, bug 136995
 skip-if = !debug
 [browser_startup.js]
 [browser_startup_content.js]
-skip-if = !e10s
+skip-if = !e10s || verify
 [browser_startup_flicker.js]
 run-if = debug || devedition || nightly_build # Requires startupRecorder.js, which isn't shipped everywhere by default
 [browser_tabclose_grow.js]