In d8, run with --runtime-call-stats and it will output the stats when d8 finishes.

In Chrome, run the following: (only on trusted code, this punches *massive* security hole into Chrome)

chrome --js-flags="--runtime-call-stats --allow-natives-syntax"

To get the stats in the console, just run

console.log(%GetAndResetRuntimeCallStats());

To output stats every second:

setInterval(function() { console.log(%GetAndResetRuntimeCallStats()); }, 1000)

Review URL: https://codereview.chromium.org/1615943002

Cr-Commit-Position: refs/heads/master@{#33462}