WebXR experience crashing when given poor data and low resources (I assume)

[blundellj]

Sony Experia XZ2 Compact
Android 10; H8314 Bulid/52.1.A.3.137
Chrome 80.0.4389.105
WebXR experience on Dev API multi-model AR test, April 1

Issue:
It seems if Voyager tries to spend too long placing the model it will crash the web page or just exit out of chrome (the webpage just reloads when you open chrome). This seems to only happen if I have a bunch of other apps running in the background. It does not happen when plugged into a computer for USB debugging.

Steps to reproduce:

• Open up a bunch of resource hogging apps in the background
• Start the multi-model AR test scene on the dev api
• keep the devices camera close to a relatively low detail surface so that the image stays out of focus (I used mono-colored cloth or mono-colored sheets of plastic)
• Move the device around on the same plane as the surface you are capturing keeping it out of focus, try to avoid any interesting details
• Eventually the web page should crash or the device will just quit out to the desktop, sometimes after capturing the out of focus surface for a while, quickly switching to a different view (such as just looking up at the room you are in) will trigger the crash/quit

[gjcope]

Improved in #69 but could be revisited.