src/vs/base/common/observableImpl/derived.ts/Derived/endUpdate
class Derived:	public endUpdate(): void {
		this.updateCount--;
		if (this.updateCount === 0) {
			if (this.observers.size > 0) {
				// Propagate invalidation
				this.get();
			}

			for (const r of this.observers) {
				r.endUpdate(this);
			}
		}
	}