We decided to move the support for the IE9 to the compatibility.js (see #4420).

I'm not finding the use of new Uint32Array() and polyfill for that. Let's special-case it in compatibility.js: for Uint32Array constructor with array, and we will create/return an object instead with the numerical index setters that will tweak the array's items. (CanvasPixelArray may be extended to return itself in the buffer getter as well). Let me know I you need help with creating such polyfill.