I ran into a problem on gruntjs/grunt-contrib-uglify#44 which required a tweak to emit the same IE-safe /* */ wrapper around the sourceMappingURL comment which was added in #108. It seems like a bad idea for all callers to need to make that same change in multiple locations but the current implementation is hard-coded into the bin script:

https://github.com/mishoo/UglifyJS2/blob/master/bin/uglifyjs#L301

What do you think about refactoring that to the OutputStream class so other tools can request the sourcemap comment without having to hard-code it?