message: Remove assertion for createdAt file
diff: @@ -55,7 +55,6 @@ PreheatedCacheCreatedAt(NSURL *preHeatedCacheDirectory, NSError * __autoreleasin
  NSDate *preheatedCacheCreatedAt = [[ISO8601DateFormatter new] dateFromString:[NSString stringWithContentsOfURL:preheatedCacheCreatedAtURL
  encoding:NSUTF8StringEncoding
  error:error]];
  - NSCParameterAssert(preheatedCacheCreatedAt);
  return preheatedCacheCreatedAt;
  }
  