support custom build of fabricjs

[mtrabelsi]

Hi, it looks like that this library is build only for minimalist fabric js (no custom build: no eraser plugin etc..)

so this code does not work

editor?.canvas.freeDrawingBrush = new fabric.EraserBrush(canvas);

freeDrawingBrush is considered as a property so no possible to set it. there is no setter either.