Fixing cache issue with VR

Babylon/babylon.scene.js

@@ -1063,6 +1063,7 @@ var BABYLON;
             // Viewport
             engine.setViewport(this.activeCamera.viewport);
             // Camera
+            this.resetCachedMaterial();
             this._renderId++;
             this.updateTransformMatrix();
             if (this.beforeCameraRender) {

Babylon/babylon.scene.ts

@@ -1371,6 +1371,7 @@
             engine.setViewport(this.activeCamera.viewport);
 
             // Camera
+            this.resetCachedMaterial();
             this._renderId++;
             this.updateTransformMatrix();
 

babylon.2.1-beta.debug.js

@@ -13067,6 +13067,7 @@ var BABYLON;
             // Viewport
             engine.setViewport(this.activeCamera.viewport);
             // Camera
+            this.resetCachedMaterial();
             this._renderId++;
             this.updateTransformMatrix();
             if (this.beforeCameraRender) {