in escodegen.js [2469:2487]
CodeGenerator.prototype.generateStatement = function (stmt, flags) {
var result,
fragment;
result = this[stmt.type](stmt, flags);
// Attach comments
if (extra.comment) {
result = addComments(stmt, result);
}
fragment = toSourceNodeWhenNeeded(result).toString();
if (stmt.type === Syntax.Program && !safeConcatenation && newline === '' && fragment.charAt(fragment.length - 1) === '\n') {
result = sourceMap ? toSourceNodeWhenNeeded(result).replaceRight(/\s+$/, '') : fragment.replace(/\s+$/, '');
}
return toSourceNodeWhenNeeded(result, stmt);
};