Fix ReferenceProperty circular event
Fix ReferenceProperty circular event

Since ReferenceProperty registered for the changed event of the collection it is inside of,
it can generate a circular raiseEvent call that ultimately leads to a stack overflow.
We add a boolean to keep track of whether we raised the event we are in and ignore subsequent calls until we exit.

josh-bernstein/cesium,aelatgt/cesium,esraerik/cesium,AnalyticalGraphicsInc/cesium,likangning93/cesium,YonatanKra/cesium,YonatanKra/cesium,aelatgt/cesium,wallw-bits/cesium,josh-bernstein/cesium,esraerik/cesium,jasonbeverage/cesium,jason-crow/cesium,YonatanKra/cesium,AnimatedRNG/cesium,emackey/cesium,progsung/cesium,CesiumGS/cesium,AnimatedRNG/cesium,esraerik/cesium,CesiumGS/cesium,hodbauer/cesium,likangning93/cesium,likangning93/cesium,omh1280/cesium,hodbauer/cesium,CesiumGS/cesium,wallw-bits/cesium,kiselev-dv/cesium,NaderCHASER/cesium,geoscan/cesium,jason-crow/cesium,emackey/cesium,NaderCHASER/cesium,YonatanKra/cesium,kiselev-dv/cesium,aelatgt/cesium,soceur/cesium,omh1280/cesium,AnimatedRNG/cesium,soceur/cesium,jasonbeverage/cesium,likangning93/cesium,aelatgt/cesium,likangning93/cesium,jason-crow/cesium,ggetz/cesium,AnimatedRNG/cesium,denverpierce/cesium,wallw-bits/cesium,hodbauer/cesium,oterral/cesium,oterral/cesium,emackey/cesium,omh1280/cesium,denverpierce/cesium,denverpierce/cesium,kaktus40/cesium,kiselev-dv/cesium,NaderCHASER/cesium,AnalyticalGraphicsInc/cesium,ggetz/cesium,oterral/cesium,jason-crow/cesium,wallw-bits/cesium,geoscan/cesium,ggetz/cesium,soceur/cesium,omh1280/cesium,kaktus40/cesium,kiselev-dv/cesium,denverpierce/cesium,ggetz/cesium,emackey/cesium,CesiumGS/cesium,esraerik/cesium,CesiumGS/cesium,progsung/cesium