I've downloaded the most recent version of compiler and i've tried to optimize js code with these flags:

java -jar closure-compiler-v20211006.jar -W VERBOSE -O WHITESPACE_ONLY --language_out ECMASCRIPT5 $script_path_in --js_output_file $script_path_tmp

closure compiler has optimized this lines of code:

for(var extraProperty of extraProperties){  
    option.setAttribute(extraProperty,initialOption[extraProperty]);    
}

into

for (var $jscomp$iter$0 = $jscomp.makeIterator(extraProperties), $jscomp$key$extraProperty = $jscomp$iter$0.next(); !$jscomp$key$extraProperty.done; $jscomp$key$extraProperty = $jscomp$iter$0.next()) {
        var extraProperty = $jscomp$key$extraProperty.value;
        {
            option.setAttribute(extraProperty, initialOption[extraProperty])
        }
    }

And as a result i receive such error in browser:

all_compressed.js Uncaught ReferenceError: $jscomp is not defined

Is there a way to change language spec with this compiler without adding side dependencies into the project, or maybe it's a bug?

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