remove unsupported negative lookbehind regex
remove unsupported negative lookbehind regex

- cherry pick from unreleased branch

carlokok/highlight.js,isagalaev/highlight.js,highlightjs/highlight.js,highlightjs/highlight.js,highlightjs/highlight.js,carlokok/highlight.js,highlightjs/highlight.js,carlokok/highlight.js,carlokok/highlight.js,isagalaev/highlight.js