src/vs/base/browser/dom.ts/SizeUtils/getDimension
class SizeUtils:	private static getDimension(element: HTMLElement, cssPropertyName: string, jsPropertyName: string): number {
		const computedStyle = getComputedStyle(element);
		const value = computedStyle ? computedStyle.getPropertyValue(cssPropertyName) : '0';
		return SizeUtils.convertToPixels(element, value);
	}