@karlis, I am not sure what was making it visible in these browsers for me, but I was able to fix it in a few different ways.
Assigning one of the following styles to the element you add to the dom:
This would make it so you cannot calculate the height of the text, but you could assign the style only after calculating the height.
top:0 or bottom:0
This should allow you to calculate height still
If you do not want to add any of those styles to this element, can you at least add some class so people know it is coming from ZoomCharts and allow us to add these extra styles ourselves? It took me a little while to figure out where this element was coming from.
With all that being said, I don't believe leaving a superfluous DOM element is a good thing, and my vote would be to remove it after you are done, or find another way to calculate the height.
Even though it is not supposed to be visible, this would still be caught by screen readers correct? At the very least I would recommend adding some code to avoid that.