Bug 1540401 - Backout Part 4: Convert MOZ_DIAGNOSTIC_ASSERT back to MOZ_ASSERT since bug 1541771 hasn't been fixed yet; r=asuth

dom/localstorage/ActorsParent.cpp

@@ -2925,7 +2925,7 @@ void InitUsageForOrigin(const nsACString& aOrigin, int64_t aUsage) {
     gUsages = new UsageHashtable();
   }
 
-  MOZ_DIAGNOSTIC_ASSERT(!gUsages->Contains(aOrigin));
+  MOZ_ASSERT(!gUsages->Contains(aOrigin));
   gUsages->Put(aOrigin, aUsage);
 }