Run:

gulp runtests-browser --t='fourslash/commentsClassMembers.ts' --browser=chrome

Expected: the test passes

Actual: "TypeError: Illegal invocation at getCompletionData (bundle.js:54363)"

This line is a call to timestamp in performance.ts

In performance.ts, changing this line from

    export const timestamp = typeof performance !== "undefined" && performance.now ? performance.now : Date.now ? Date.now : () => +(new Date());

     export const timestamp = () => Date.now();

fixes the bug. Searching indicates that this error happens when you try to call an function without providing the expected this, like performance.now or Date.now. Node and Chrome are OK with ripping off Date.now, so I suspect it's performance.now.