Fengist
It doesn't crash for me either, and I'm not sure why you'd be running into a memory limit with asm.js in your capx.
One thing that does stand out is sprite3 is animated. The physics engine has to re-calculate the collision polygon every time the frame changes, which I guess may be using up memory. Often what I do is create an invisible second object with one frame to handle the physics, and then remove physics from the animated object and pin it to the other object.
Also you can avoid the memory limit entirely by changing "project properties"->"Physics engine" from "asm.js box2d" to "box2d web". The only difference is the performance may not be as good.