three fixes that allow web (js) to work for cogentcore

[rcoreilly]

• remove debugging print and toJS() call that fails with nil in RequestDevice
• DepthStencilState changed to an OptionalBool depthWriteEnabled and depthCompare fields in GPUDepthStencilState are optional in spec gfx-rs/wgpu#8830
• RenderPassDepthStencilAttachment conditional logic that was missing in cogentcore version.

[rcoreilly]

@oliverbestmann tagging you just in case notifications don't work :)

[oliverbestmann]

Thank you!