Comments are only output the first time an AST is serialized

[papandreou]

var uglifyJs = require('uglify-js');

function serialize(ast) {
    var outputStream = uglifyJs.OutputStream({comments: true});
    ast.print(outputStream);
    return outputStream.get();
}

var ast = uglifyJs.parse('/*foo*/ var isIe = /*@cc_on true ||*/ false;');

console.warn("first time:", serialize(ast));
console.warn("second time:", serialize(ast));

Output:

first time: /*foo*/var isIe=/*@cc_on true ||*/false;
second time: var isIe=false;

The error occurs because start._comments_dumped isn't reset after the serialization: https://github.com/mishoo/UglifyJS2/blob/master/lib/output.js#L384-L385

[papandreou]

@mishoo This bug is still present. Could you please comment?