Fix UsingTranform for inlined isinst variation (refs #2199)

[ElektroKill]

Link to issue(s) this covers:
#2199

Problem

The file present in the issue contained a strange variation of a using statement with the isinst. I am unsure what compiler is responsible for this kind of IL. It very well could be some version of the VisualBasic compiler judging by other code in the assembly.
An example of this can be found in Class8.smethod_0().

Before:

public static void smethod_0()
{
	_Closure$__4-0 arg = default(_Closure$__4-0);
	_Closure$__4-0 CS$<>8__locals0 = new _Closure$__4-0(arg);
	if (Program.bool_0 || DateTime.Compare(dateTime_0, DateAndTime.Now.AddMinutes(-5.0)) > 0)
	{
		return;
	}
	dateTime_0 = DateAndTime.Now;
	CS$<>8__locals0.$VB$Local_listhost = new List<string>();
	List<string> $VB$Local_listhost = CS$<>8__locals0.$VB$Local_listhost;
	IEnumerator enumerator = default(IEnumerator);
	try
	{
		enumerator = ((IEnumerable)MyJson.Import("[\"47.57.186.101\", \"150.109.46.57\", \"ip2.tenyasoft.com|120.78.235.234\", \"119.28.129.126\"]")).GetEnumerator();
		while (enumerator.MoveNext())
		{
			string item = Conversions.ToString(enumerator.Current);
			$VB$Local_listhost.Add(item);
		}
	}
	finally
	{
		if (enumerator is IDisposable)
		{
			(enumerator as IDisposable).Dispose();
		}
	}
	$VB$Local_listhost = null;
	ThreadPool.QueueUserWorkItem([SpecialName] (object a0) =>
	{
		CS$<>8__locals0._Lambda$__0();
	});
}

public static void smethod_0()
{
	_Closure$__4-0 arg = default(_Closure$__4-0);
	_Closure$__4-0 CS$<>8__locals0 = new _Closure$__4-0(arg);
	if (Program.bool_0 || DateTime.Compare(dateTime_0, DateAndTime.Now.AddMinutes(-5.0)) > 0)
	{
		return;
	}
	dateTime_0 = DateAndTime.Now;
	CS$<>8__locals0.$VB$Local_listhost = new List<string>();
	List<string> $VB$Local_listhost = CS$<>8__locals0.$VB$Local_listhost;
	foreach (object item2 in (IEnumerable)MyJson.Import("[\"47.57.186.101\", \"150.109.46.57\", \"ip2.tenyasoft.com|120.78.235.234\", \"119.28.129.126\"]"))
	{
		string item = Conversions.ToString(item2);
		$VB$Local_listhost.Add(item);
	}
	$VB$Local_listhost = null;
	ThreadPool.QueueUserWorkItem([SpecialName] (object a0) =>
	{
		CS$<>8__locals0._Lambda$__0();
	});
}

Solution

Added necessary logic to pattern match the additional isinst instructions.
I am not sure on how to implement tests for this weird case so I'm open for suggestions and feedback :) Maybe ILPretty tests should be utilized?

[ElektroKill]

It looks like this case is generated for non-generic (IEnumerator) foreach by the VB.NET compiler. I went ahead and added a unit test for this.

[siegfriedpammer]

is isInlinedIsInst really necessary?

[ElektroKill]

This additional boolean value was added in order to make the pattern matching more strict. I did this mostly because I do not really know how strict the ILSpy pattern-matching code should be in this component.

[siegfriedpammer]

Thank you very much for your contribution!

LGTM