Reset cached index buffer on render begin.
Reset cached index buffer on render begin.

--HG--
branch : feature/json-loader

sanyaade-teachings/engine,shinate/engine,sereepap2029/playcanvas,horryq/engine-1,sereepap2029/playcanvas,3DGEOM/engine,sanyaade-teachings/engine,aidinabedi/playcanvas-engine,MicroWorldwide/PlayCanvas,3DGEOM/engine,H1Gdev/engine,RainsSoft/engine,MicroWorldwide/PlayCanvas,playcanvas/engine,nizihabi/engine,playcanvas/engine,maxwellalive/engine,sanyaade-teachings/engine,RainsSoft/engine,H1Gdev/engine,3DGEOM/engine,nizihabi/engine,aidinabedi/playcanvas-engine,SuperStarPL/engine,sereepap2029/playcanvas,RainsSoft/engine,maxwellalive/engine,shinate/engine,shinate/engine,SuperStarPL/engine,horryq/engine-1,horryq/engine-1,guycalledfrank/engine,maxwellalive/engine,guycalledfrank/engine,nizihabi/engine,SuperStarPL/engine