Update Emdawnwebgpu port to v20250531.224602

[kainino0x]

Release page: https://github.com/google/dawn/releases/tag/v20250531.224602

Emdawnwebgpu releases now generate these "remoteport" files, which can be copied directly into Emscripten. The README is just included in the file for people who download it from Dawn's releases page because it's a single file download - I don't expect --use-port=emdawnwebgpu users to read it.

I thought about including a link to the README (https://dawn.googlesource.com/dawn/+/ea66c0fa309f01f2ba1ec2fd2c680cc992eaf72a/src/emdawnwebgpu/pkg/README.md) in the DESCRIPTION but I don't think the description is user-visible? (It doesn't show up in --show-ports.) It would be nice to make sure the readme is findable by users.

This is tested by test_remote_ports and test_emdawnwebgpu_link_test.

[ypujante]

As an FYI, yes description is user visible, when using the help option:

# on my older branch...
> emcc --use-port=emdawnwebgpu:help 
emdawnwebgpu (--use-port=emdawnwebgpu; mixed licenses, see license files)
Emdawnwebgpu is a fork of Emscripten's original USE_WEBGPU, implementing a newer, more stable version of the standardized webgpu.h interface. If you find issues, verify in the latest nightly release (https://github.com/google/dawn/releases) and file feedback with Dawn. (Emdawnwebgpu is maintained as part of Dawn, the open-source WebGPU implementation used by Chromium, but it is still cross-browser.)
Options:
* cpp_bindings: Add the include path for <webgpu/webgpu_cpp.h> C++ bindings. Default: true.
* opt_level: Optimization (-O) level for the bindings' Wasm layer. Default: choose based on -sASSERTIONS.
More info: https://dawn.googlesource.com/dawn/+/refs/heads/main/src/emdawnwebgpu/

[kainino0x]

Ahh of course, that's where it would be, thank you. I will update it at some point then.