Parameterize test_webgl_offscreen_framebuffer_state_restoration. NFC

[sbc100]

No description provided.

[sbc100]

Split out from #23056

[kainino0x]

I didn't realize that this whole mess was fully my doing (#8037). I checked there and the TEST_VAO vs TEST_REQUIRE_VAO thing was just wrong from the beginning. Probably I tried to refactor something during the PR and did it incompletely.

However from looking at that PR I think I have figured out what the intent was: not to enable the extension, but to verify that it was supported so we could be sure that OffscreenFramebuffer would be using it.

Yesterday I was confused about what would actually be enabling it for OffscreenFramebuffer to use, but that was because I thought emscripten_webgl_create_context wouldn't enable it. But it does, because GL_SUPPORT_AUTOMATIC_ENABLE_EXTENSIONS=1 by default.

Back when I originally wrote this I'm not sure there was such an option, or at least it was phrased differently. But I think what this means is if GL_SUPPORT_AUTOMATIC_ENABLE_EXTENSIONS=0 then the VAO path will never be used on webgl1, because the extension won't be enabled early enough to hit it.

[sbc100]

Thanks @kainino0x !