How to hide canvas content from parent rounded corners in any webkit for Mac?

Question

I have a parent div with rounded corners that contains a canvas:

Answer 1

This is what I found out:

In the canvas element, when the multiplication of width by height is 66000 or greater, the canvas ignores the parent's overflow property.

For example, the following one fails, because 300*220 = 66000

This one works fine:

I've found this bug report after googling for "canvas 66000". It is not related with overflow, but I am sure is the same bug.

Thanks for Jeemusu for pointing me in the right direction.