Bug 1493060 - Convert an overly aggressive assertion into a runtime check r=baku

None of the callers of this function ensure the argument passed
down here is actually a tracking window, so we need to properly
check it here rather than merely assert.

Differential Revision: https://phabricator.services.mozilla.com/D6458

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

toolkit/components/antitracking/AntiTrackingCommon.cpp

@@ -65,7 +65,9 @@ GetParentPrincipalAndTrackingOrigin(nsGlobalWindowInner* a3rdPartyTrackingWindow
                                     nsIPrincipal** aTopLevelStoragePrincipal,
                                     nsACString& aTrackingOrigin)
 {
-  MOZ_ASSERT(nsContentUtils::IsTrackingResourceWindow(a3rdPartyTrackingWindow));
+  if (!nsContentUtils::IsTrackingResourceWindow(a3rdPartyTrackingWindow)) {
+    return false;
+  }
 
   nsIDocument* doc = a3rdPartyTrackingWindow->GetDocument();
   // Make sure storage access isn't disabled