UserAgent: Mozilla/5.0 (X11; CrOS x86_64 9592.96.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.114 Safari/537.36
Platform: Any

Steps to reproduce the problem:
1. Visit this website: trusktr.io/polydance (on a desktop OS)
2. Record in the Performance tab for a few seconds.
3. Look in the timeline and for each animation frame notice that sometimes the `motorLoop` function is split into two or more sections.

What is the expected behavior?
The `motorLoop` function is only called once per animation frame, so I would expect to always see a single continuous bar for the `motorLoop` calls.

What went wrong?
Sometimes, the bar representing the `motorLoop` calls are split into two or more sections, giving the impression that the `motorLoop` function is being called more than once per frame, but this is not the case.

I can verify that this isn't the case because I can monkey patch `requestAnimationFrame` to log something at the beginning and end of each frame, and I can make `motorLoop` log something as well, and the console.log statement inside `motorLoop` is only ever logged once between the two outer start/end logs of the animation frame.

Did this work before? Yes Not sure.

Chrome version: 60.0.3112.114  Channel: n/a
OS Version: 9592.96.0
Flash Version: 

I've never noticed this behavior until now.

Something that I noticed is that the splitting of the `motorLoop` function's timeline bar is always during points of numerous calls to WebGL APIs. It never happens before the calls to the WebGL APIs.

You'll see a `drawScene` function which is the function that encapsulates all the WebGL calls, and the split always happens during the `drawScene` call inside of the `motorLoop` call.

`motorLoop` is the root function inside the animation frames, besides the microtask stuff which is Vue.js related.