src/vs/workbench/services/views/common/viewContainerModel.ts/ViewContainerModel/isVisible
class ViewContainerModel:	isVisible(id: string): boolean {
		const viewDescriptorItem = this.viewDescriptorItems.find(v => v.viewDescriptor.id === id);
		if (!viewDescriptorItem) {
			throw new Error(`Unknown view ${id}`);
		}
		return this.isViewDescriptorVisible(viewDescriptorItem);
	}