Bug 1877957 p4: Enable untrusted integrity for content process sandbox on Nightly. r=handyman

Differential Revision: https://phabricator.services.mozilla.com/D200796

browser/app/profile/firefox.js

@@ -1404,7 +1404,11 @@ pref("browser.bookmarks.editDialog.maxRecentFolders", 7);
   // On windows these levels are:
   // See - security/sandbox/win/src/sandboxbroker/sandboxBroker.cpp
   // SetSecurityLevelForContentProcess() for what the different settings mean.
-  pref("security.sandbox.content.level", 6);
+  #if defined(NIGHTLY_BUILD)
+    pref("security.sandbox.content.level", 7);
+  #else
+    pref("security.sandbox.content.level", 6);
+  #endif
 
   // Pref controlling if messages relevant to sandbox violations are logged.
   pref("security.sandbox.logging.enabled", false);