WebGPURenderer: Fix issues in WebXR caused by texture array work.

[cabanier]

84b6feb introduced a couple of regressions in WebXR. This also fixes an issue where layers were drawn upside down after exiting WebXR.

cc @Mugen87

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	337.26 78.64	337.26 78.64	+0 B +0 B
WebGPU	549.21 152.28	549.52 152.34	+314 B +50 B
WebGPU Nodes	548.56 152.13	548.87 152.18	+314 B +51 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	467.34 112.95	467.34 112.95	+0 B +0 B
WebGPU	624.12 169.01	624.43 169.06	+314 B +47 B
WebGPU Nodes	578.97 158.31	579.28 158.35	+314 B +45 B

[Mugen87]

Updated builds, 980d7ca.