Could you not fullscreen it please?
It causes WebGL context to get lost, and then says to reload the page. And then it only ever says "WebGL not available" when you do. A complete shutdown and restart of the browser and go through those same steps.
I know this computer can play WebGL games as I've played plenty of them before. And if people want it fullscreened, not difficult for them to just F11.
In general, you should never default games to fullscreen.
Since I can't play it or even evaluate the quality I don't know what else to rate it but a 0 at the moment. Not because it might not be good, but because as-is, it is just broken for me, until you fix the defaulting to fullscreen thing. I see the game has already passed judgment, so this should not cause it to "blam".
Please default games only to windowed modes, and if someone wants it fullscreen, let them make that decision, instead of you making that decision for them.
--edit--
Hmm. Well if you've not set it to force fullscreen, it's still behaving badly. What it does is the entire screen goes black (just like if something were to be fullscreened, right before the fullscreen) but then locks up and just goes back to what it was with those errors mentioned.
I can and have played many WebGL games without problems. In fact many Unity games are WebGL and I've played lots of those as that seems the most popular kind of game people submit to Newgrounds these days.
Could be your game is making some bad hardware assumptions or something, then. Maybe blindly using some functionality that only works on particular graphics card(s) without first checking that the functionality is present (and falling back to software emulation if not present).
Regardless, this does not work for me. I don't feel good giving it such a rating, but I don't know what else I can rate it when it just crashes for me and I can't even play it.
--edit--
One more thing I can think of. Does this require a too new version of OpenGL? I only have OpenGL 3.3 on this hardware. The newest version that exists is 4.6. In general, one should not use the absolute newest APIs unless one has very good reasons to do so, precisely because it will break things. You have to find the happy medium. I would guess that OpenGL 3.0 should be pretty "safe" to develop to, or if in doubt, then OpenGL 2.0.
Blender claims OpenGL 3.3 as its minimum supported version. So surely if Blender doesn't need anything newer than that, then your game shouldn't either?