Some MSTest unit tests are incorrectly marked with TestMethodAttribute

[Youssef1313]

Example:

testfx/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.IsInstanceOfTypeTests.cs

Lines 93 to 94 in af1e0e5

	[TestMethod]
	public void IsInstanceOfTypeUsingGenericType_WhenValueIsNull_Fails()