src/vs/editor/browser/view/renderingContext.ts/RestrictedRenderingContext/constructor
class RestrictedRenderingContext:	constructor(viewLayout: IViewLayout, viewportData: ViewportData) {
		this._viewLayout = viewLayout;
		this.viewportData = viewportData;

		this.scrollWidth = this._viewLayout.getScrollWidth();
		this.scrollHeight = this._viewLayout.getScrollHeight();

		this.visibleRange = this.viewportData.visibleRange;
		this.bigNumbersDelta = this.viewportData.bigNumbersDelta;

		const vInfo = this._viewLayout.getCurrentViewport();
		this.scrollTop = vInfo.top;
		this.scrollLeft = vInfo.left;
		this.viewportWidth = vInfo.width;
		this.viewportHeight = vInfo.height;
	}