While I could not recreate this behavior with newline, there was a side effect of the above change, to do with the single quote (') character which must now be escaped as well. otherwise the browser behaves as you describe.
The new behavior described above is dependent on the constant having a shared property pluginVersion=1, otherwise it should behave as it always did (that is support for \n, but not for other escaped characters, and quote not requiring escape)
If that does not ring a bell, please provide a specific example.
For best results, use the Firefox browser..