src/vs/editor/common/viewModel/viewModelImpl.ts/ViewModel/saveState
class ViewModel:	public saveState(): IViewState {
		const compatViewState = this.viewLayout.saveState();

		const scrollTop = compatViewState.scrollTop;
		const firstViewLineNumber = this.viewLayout.getLineNumberAtVerticalOffset(scrollTop);
		const firstPosition = this.coordinatesConverter.convertViewPositionToModelPosition(new Position(firstViewLineNumber, this.getLineMinColumn(firstViewLineNumber)));
		const firstPositionDeltaTop = this.viewLayout.getVerticalOffsetForLineNumber(firstViewLineNumber) - scrollTop;

		return {
			scrollLeft: compatViewState.scrollLeft,
			firstPosition: firstPosition,
			firstPositionDeltaTop: firstPositionDeltaTop
		};
	}