Fix MDN link generation for ANGLE_instanced_arrays APIs

[rdw-software]

It defaulted to the WebGL1 API root previously, resulting in a dead link being generated.

Example: drawElementsInstancedANGLE call generates link to this invalid URL

The real link uses the extension name as a prefix: https://developer.mozilla.org/en-US/docs/Web/API/ANGLE_instanced_arrays/drawArraysInstancedANGLE

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Marked as draft since I'm unsure about what to do next, and I don't know how to test that this actually fixes the issue.

Looks like there are no automated tests? Do I also need to build the bundle? Update the changelog?

Also, what about other extensions, presumably they're also broken? Hmm...

[sebavan]

I love your fix, and unfortunately automated tests might not help much when relying on external urls (they might change at some points).

Usually to test locally I just run npm start with one of the examples setup.

For specific apis, you can npm run build and side load the extension in chrome from the build folder.

I like the concern about the other extensions as well but lets do them one at a time ?

[rdw-software]

Sorry, I completely forgot about this. I tested the changes by performing the following steps:

1. npm start
2. Start local webserver
3. Access /sample/index.html?sample=instanced in Chrome
4. Record frame after the scene had finished loading
5. Select one of the calls to drawElementsInstancedANGLE in the "Commands" tab
6. Check link generated for "Open help page"

As far as I can tell, that means the fix worked and this should be good to go? If not, please do let me know.