Reverting an unintended breaking-change. (microsoft#826)

Reverting an unintended breaking change in reflection.

Thank you, @azchohfi, for reporting it; this makes microsoft#824 unnecessary.

Author: Haplois

src/Adapter/MSTest.CoreAdapter/Execution/TestMethodInfo.cs

@@ -93,7 +93,9 @@ public Attribute[] GetAllAttributes(bool inherit)
         }
 
         public TAttributeType[] GetAttributes<TAttributeType>(bool inherit)
-            where TAttributeType : Attribute => ReflectHelper.GetAttributes<TAttributeType>(this.TestMethod, inherit);
+            where TAttributeType : Attribute
+            => ReflectHelper.GetAttributes<TAttributeType>(this.TestMethod, inherit)
+            ?? EmptyHolder<TAttributeType>.Array;
 
         /// <summary>
         /// Execute test method. Capture failures, handle async and return result.
@@ -784,5 +786,10 @@ void executeAsyncAction()
                 return timeoutResult;
             }
         }
+
+        private static class EmptyHolder<T>
+        {
+            internal static readonly T[] Array = new T[0];
+        }
     }
 }