"condvar wait not supported" in wasm-bindgen tests in browser with WebGPU backend

[MaximilianAzendorf]

Describe the bug
When using burn (e.g. calling Tensor::from_data) with the WebGPU backend inside a wasm-bindgen test running on a chrome, it fails with an exception with the message "condor wait not supported".

To Reproduce
See this repository containing a minimal reproduction of this behavior.

Expected behavior
As far as I am aware, burn and the WebGPU backend support running in the browser. I therefore would expect that it is possible to use burn inside wasm-bindgen tests in a browser. If this is indeed not supported, I think that the documentation is insufficient in regards to which backend supports which platform.

Desktop (please complete the following information):

• OS: reproduced on Arch Linux and MacOS 14.5
• Browser: Chrome 126.0.6478.115
• Version: 0.13.2

[nathanielsimard]

@MaximilianAzendorf I think on wasm you got to initialize the wgpu runtime manually using

burn/crates/burn-wgpu/src/runtime.rs

Line 131 in 3faf544

pub async fn init_async<G: GraphicsApi>(device: &WgpuDevice, options: RuntimeOptions) {