Bug 1162344 - Use the exemptFromPerDomainMax pref in test_importscript.html; r=nsm

dom/workers/test/serviceworkers/test_importscript.html

@@ -62,6 +62,7 @@
 
   SimpleTest.waitForExplicitFinish();
   SpecialPowers.pushPrefEnv({"set": [
+    ["dom.serviceWorkers.exemptFromPerDomainMax", true],
     ["dom.serviceWorkers.enabled", true],
     ["dom.serviceWorkers.testing.enabled", true]
   ]}, runTest);