Please provide an example of creating a WebGPU program using offscreen canvas and webgpu_cpp.h？ about emscripten

[kripken]

cc @kainino0x

[Diyou]

Looks like CreateSurface() got broken in 3.1.52 when used in a pthread. It worked in 3.1.51.

HelloTriangle.js:240 TypeError: Cannot read properties of undefined (reading 'getContext')
    at _wgpuInstanceCreateSurface (http://localhost:6931/HelloTriangle.js:10209:24)
    at HelloTriangle.wasm.wgpu::Instance::CreateSurface(wgpu::SurfaceDescriptor const*) const (http://localhost:6931/HelloTriangle.wasm:wasm-function[5898]:0x38c609)
    at invoke_viii (http://localhost:6931/HelloTriangle.js:11034:29)
    at HelloTriangle.wasm.Context@Diyou::From(Window@Diyou const&, std::__2::function<void (Context@Diyou&&)>) (http://localhost:6931/HelloTriangle.wasm:wasm-function[386]:0xc832)
    at invoke_vii (http://localhost:6931/HelloTriangle.js:11023:29)
    at HelloTriangle.wasm.Renderer::CreateFrom(Window@Diyou&&) (http://localhost:6931/HelloTriangle.wasm:wasm-function[371]:0x8fa6)
    at invoke_vi (http://localhost:6931/HelloTriangle.js:11012:29)
    at HelloTriangle.wasm.main (http://localhost:6931/HelloTriangle.wasm:wasm-function[360]:0x781e)
    at HelloTriangle.wasm.__main_void (http://localhost:6931/HelloTriangle.wasm:wasm-function[3569]:0x346864)
    at HelloTriangle.wasm._main_thread (http://localhost:6931/HelloTriangle.wasm:wasm-function[3571]:0x3468fd)