How does llvmpipe do these days? I remember being excited about it ~5 years ago and I can only imagine both LLVM performance and CPU speeds have gone up.
But that's the part that's crashing. I'm suggesting Chrome use llvmpipe to do whatever they needed hardware acceleration for, generate a single boring texture on a single big rectangle, and pass that through to the graphics driver. That way Chrome itself isn't loading the Nouveau libGL and is much more insulated from incompatibilities between Chrome and Nouveau, whosever fault it might be.
That's why you go through llvmpipe - you use the Mesa OpeGL implementation in LLVM-JIT-accelerated but pure software mode to implement WebGL, get the results onto a texture, and pass that texture onto your actual graphics card.