Bug 1596049. Calling CheckForProcessCrashExpectation needs to pass contentRootElement otherwise it does nothing. r=mattwoodrow

Depends on D52827

Differential Revision: https://phabricator.services.mozilla.com/D52828

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

layout/tools/reftest/reftest-content.js

@@ -788,7 +788,7 @@ function WaitForTestEnd(contentRootElement, inPrintMode, spellCheckedElements, f
             state = STATE_COMPLETED;
             gFailureReason = "timed out while taking snapshot (bug in harness?)";
             RemoveListeners();
-            CheckForProcessCrashExpectation();
+            CheckForProcessCrashExpectation(contentRootElement);
             setTimeout(RecordResult, 0, forURL);
             return;
         }