A Firefox WebExtension that replaces the best-effort text rendering GitHub does for the WebAssembly binary format with an on-the-fly generated text format representation of the same file.
While GitHub does syntax highlighting for the WebAssembly text format, it does so on the server, so at least for now the rendered text will not have any highlighting.
The extension can be installed from its addons.mozilla.org listing.
After installation, verify that the extension works as expected by visiting the demo wasm file.
After changing the extension source, go to about:debugging and load it as a temporary add-on. Once you've verified that everything works as expected, you can bundle it as a zip file. To install it permanently, it has to be turned into a signed extension. At this point, either just send a pull request, or publish your fork on addons.mozilla.org.