Test that the window.navigator.xr wrapper preserves custom properties.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".


PASS window.navigator.xr.customProperty is undefined.
window.navigator.xr.customProperty = 1
PASS window.navigator.xr.customProperty is 1
PASS window.navigator.xr.customProperty is 1
PASS window.navigator.xr.customProperty is 1
PASS window.navigator.xr.customProperty is 1
PASS successfullyParsed is true

TEST COMPLETE