Comments function has been refactored to use substring instead of substr

[ayxos]

Some customers have the following creatives:

function markup() {/*
    <_test!doctype html>
    <_testhtml>
      <_testhead></_testhead>
      <_testbody style="margin:0px">
        <_testh1> This is a Test </_testh1>
        <_testdiv class="test_creative" style="width:320px;height:50px;">
            <_testscript type='text/javascript'>
                console.log('TEST')
            </_testscript>
        </_testdiv>
        </_testbody>
    </_testhtml>
*/}
function parsingFn(func) {
    return func.toString().replace(/(<|\*)(\/)?_test/g,"$1$2").split(/\n/).slice(1, -1).join('\n');
}
document.write(parsingFn(markup));
document.close();

Which is not working with the current version of Postscribe. The PR fixes the problem