Bug 948774: Followup to tweak an assertion. r=me

dom/ipc/ContentParent.cpp

@@ -1242,10 +1242,12 @@ ContentParent::ContentParent(mozIApplication* aApp,
 {
     InitializeMembers();  // Perform common initialization.
 
-    // No more than one of !!aApp, aIsForBrowser, aIsForPreallocated, and
-    // aIsNuwaProcess should be true.
-    MOZ_ASSERT(!!aApp + aIsForBrowser + aIsForPreallocated + aIsNuwaProcess <=
-               1);
+    // No more than one of !!aApp, aIsForBrowser, aIsForPreallocated should be
+    // true.
+    MOZ_ASSERT(!!aApp + aIsForBrowser + aIsForPreallocated <= 1);
+
+    // Only the preallocated process uses Nuwa.
+    MOZ_ASSERT_IF(aIsNuwaProcess, aIsForPreallocated);
 
     // Insert ourselves into the global linked list of ContentParent objects.
     if (!sContentParents) {