Low priority: Custom builds require 'Animation' to be checked

[joevallender]

I'm using Fabric for part of an app that requires very limited dragging and rotation of images across desktop and mobile so I headed to http://fabricjs.com/build/ to include the gestures and slim the file size down a bit.

The resulting build kept throwing an error relating to fabric.util.requestAnimFrame despite me only using Gestures/Interaction/fabric.Image. I tried a build with Animation checked and it was okay. No big deal in my use case. However I thought I'd flag it.

Also that page says its building v4.1.0 but its actually outputting v5.2.0

I'll take a quick look at a PR to the text on /build/

[asturur]

it could be that requestRenderAll uses that, in case we should move requestAnimFrame outside the util module