Texture fixes (#1291)
Texture fixes (#1291)

* Don't run high precision float render test of float render is not supported by device.
* Correctly bind render target texture for mipmap generation.
* Unset a destroyed texture from any scope ids.
MicroWorldwide/PlayCanvas,MicroWorldwide/PlayCanvas,sereepap2029/playcanvas,aidinabedi/playcanvas-engine,sereepap2029/playcanvas,playcanvas/engine,aidinabedi/playcanvas-engine,sereepap2029/playcanvas,playcanvas/engine