e10s: Wheel Gestures don't prevent page scrolling

[monk-time]

Before I have force-enabled e10s, it was very convenient that Wheel Gestures didn't allow a page to scroll if I had enabled Wheel Gestures in the options. But with e10s the gesture is executed only after a page is scrolled by a notch, and that makes Wheel Gestures less useful (e.g. Next/Previous Tab shifts all tabs when scrolling rapidly through them).

I assume it is related to Async Pan/Zoom module (APZ), it is enabled on desktop only with e10s.

FF 50.0.2, Win7x64, FireGestures 1.10.13