Tracking-vector image should be marked darkmode-aware

[Kaiido]

In whatwg/whatwg.org#444 the tracking-vector svg from whatwg has been made darkmode-aware, however for it to render properly without a white background, it needs a class="darkmode-aware".

Looking at the source it seems there is an inline fallback that is not darkmode-aware. It also seems that every consumer could define their own source for the image file? That would probably make things harder to fix.

[tabatkins]

Ooh, thanks for pointing this out. I've gone ahead and made my inline image darkmode-aware, and added the class to the generated img. I've noted in the docs that the external image (if provided) must be darkmode-aware as well.