You can use this as yield return CoroutineWatier(YourCoroutineHere());

CoroutineWaiter.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;

public class CoroutineWaiter : IEnumerator {
	public bool IsFinished { get; private set; }
	private readonly Action _onFinish;
	readonly Stack<IEnumerator> _stack= new Stack<IEnumerator>();
	

	public CoroutineWaiter(IEnumerator enumerator, Action onFinish = null)
	{
		IsFinished = false;
		_onFinish = onFinish;
		_stack.Push(enumerator);
	}
	
	public bool MoveNext()
	{
		UnityEngine.Debug.Log("move next");
		while (_stack.Count > 0 && !_stack.Peek().MoveNext())
		{
			_stack.Pop();
		}
		if (_stack.Count == 0)
		{
			IsFinished = true;
			if (_onFinish != null)
			{
				_onFinish();
			}
			return false;
		}
		IEnumerator activeEnum = _stack.Peek();
		if (activeEnum.Current != activeEnum && activeEnum.Current is IEnumerator )
		{
			_stack.Push(activeEnum.Current as IEnumerator);	
		}
		return true;
	}

	public void Reset()
	{
		_stack.Clear();
	}

	public object Current
	{
		get { return _stack.Peek(); }		
	}
}