src/vs/editor/common/viewModel/viewModelImpl.ts/ViewportStart/create
class ViewportStart:	public static create(model: ITextModel): ViewportStart {
		const viewportStartLineTrackedRange = model._setTrackedRange(null, new Range(1, 1, 1, 1), TrackedRangeStickiness.NeverGrowsWhenTypingAtEdges);
		return new ViewportStart(model, 1, false, viewportStartLineTrackedRange, 0);
	}