[ExcludeFromCodeCoverage] lets through lambdas, yield return and await

[SteveGilham]

This code

    public class Class1
    {
        [ExcludeFromCodeCoverage]
        public int F1(string input)
        {
            Func<char, int> f = (c => { return (int)c; });

            return input.Select(x =>
            {
                var l = new List<char> { x };
                return l.Select(f).Last();
            }).Sum();
        }

        [ExcludeFromCodeCoverage]
        public IEnumerable<int> F2(string input)
        {
            foreach (char c in input)
            {
                yield return c;
            }
        }

        [ExcludeFromCodeCoverage]
        public async Task<string> F3(string input)
        {
            var f = new StreamReader(File.OpenRead(input));
            var r = await f.ReadToEndAsync();
            return r;
        }

        public static string F4(string input)
        {
            return input.ToUpperInvariant();
        }

        [ExcludeFromCodeCoverage]
        public string F5(string input)
        {
            return input.ToUpperInvariant();
        }
    }

with a test to exercise method F4.

Expect just method F4 in the coverage file, with 100% coverage
Get 15.8% line coverage, with the lambda expressions in F1 and generated MoveNext methods in the implementations of F2 and F3 showing uncovered.

[SteveGilham]

The async/await case is the equivalent of OpenCover's issue #779.

[MarcoRossignoli]

Possible related to #343
Unrelated...the issue is due to state machine generated for a method...that new type doesn't have exclude attrib applied.