Fix CubeMap Seams bug on A12 and A12X chips (#1465)
Fix CubeMap Seams bug on A12 and A12X chips (#1465)

A12 and A12X chips (late 2018 iPhones and iPads) had a regression in their WebGL implementation which removed a feature of CubeMaps seams filtering on the faces edges.
So disabling the `unmaskedRenderer` forces engine to use manual seams path which avoids an issue.
MicroWorldwide/PlayCanvas,sereepap2029/playcanvas,sereepap2029/playcanvas,playcanvas/engine,MicroWorldwide/PlayCanvas,aidinabedi/playcanvas-engine,aidinabedi/playcanvas-engine,playcanvas/engine,sereepap2029/playcanvas