They don't try to make it difficult, but they make code changes that make it clear they have no concern for anyone who might be trying to use the engine anywhere other than in a retail build of Firefox, without providing things like deprecation warnings or upgrade paths.
They don't try to make it difficult, but they make code changes that make it clear they have no concern for anyone who might be trying to use the engine anywhere other than in a retail build of Firefox, without providing things like deprecation warnings or upgrade paths.