css reflows caused by old fix for IE8

retest / consider removing the implementation of ZK-1885 for modern browsers

consider the simple example:

<zk>
	<div vflex="1" width="100%" style="border: 1px solid red;">
		<vlayout vflex="1" hflex="1">
			<forEach begin="1" end="5" varStatus="outer">
				<hlayout vflex="1" hflex="1">
					<forEach begin="1" end="10" varStatus="inner">
						<div hflex="1">
							${outer.index}-${inner.index}
						</div>
					</forEach>
				</hlayout>
			</forEach>
		</vlayout>
	</div>
</zk>

manually counting the "forced reflow" warnings in chrome developer tools resulted in ~150 warnings

more complex examples easily result in 1000s of reflows = bad performance

Where possible first collect read styles of multiple/all affected widgets, then update styles (only if needed!) in a separate loop.
Avoid alternating between read/update/read/update styles
Most prominent example in zk.Widget.resetSize

https://github.com/zkoss/zk/blob/master/zk/src/archive/web/js/zk/widget.js#L3367-L3372

Here n.scrollTop/n.ScrollLeft trigger a css reflow followed by an immediate style update.
The next call to resetSize will reflow/update again

A nice collection of what might cause a reflow is summarized here: What forces layout / reflow