Bug 1513101 - re-add L section for HANDLES_DUP_BROKER to RDD Win sanbox to fix mochitest crashes. r=bobowen

Differential Revision: https://phabricator.services.mozilla.com/D14109

--HG--
extra : moz-landing-system : lando

security/sandbox/win/src/sandboxbroker/sandboxBroker.cpp

@@ -753,6 +753,16 @@ bool SandboxBroker::SetSecurityLevelForRDDProcess() {
       result,
       "With these static arguments AddRule should never fail, what happened?");
 
+  // This section is needed to avoid an assert during crash reporting code
+  // when running mochitests.  The assertion is here:
+  // toolkit/crashreporter/nsExceptionHandler.cpp:2041
+  result =
+      mPolicy->AddRule(sandbox::TargetPolicy::SUBSYS_HANDLES,
+                       sandbox::TargetPolicy::HANDLES_DUP_BROKER, L"Section");
+  SANDBOX_ENSURE_SUCCESS(
+      result,
+      "With these static arguments AddRule should never fail, what happened?");
+
   return true;
 }