consider not rounding dimensions in onResize method

[dougbacelar]

The onResize method in dom.js currently uses offsetWidth and offsetHeight to get the elements dimensions.

These two attributes always return integer values--disregarding the fractional part

• https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/offsetWidth
• https://bugs.chromium.org/p/chromium/issues/detail?id=360889

As some elements can have subpixel values, perhaps its worth it considering not to round the width and height to achieve a better precision.

I believe this is also causing the zoid library to sometimes generate slightly wrong iframe sizes, since the method seems to be used here

• this can cause scrollbars to appear in the iframes if the dimensions generated are smaller than the element dimensions

In case you are interested, I opened a draft PR with a suggested approach:

• https://github.com/krakenjs/belter/pull/66/files