Fix for Dictinonary.ContainsKey (Move the call after the restore of field state)

Author: JonathanMagnan

src/System.Linq.Dynamic.Core/Parser/ExpressionParser.cs

@@ -1740,15 +1740,15 @@ Expression ParseEnumerable(Expression instance, Type elementType, string methodN
 
             Expression[] args = ParseArgumentList();
 
+            _it = outerIt;
+            _parent = oldParent;
+
             if (isDictionary && _methodFinder.ContainsMethod(typeof(IDictionarySignatures), methodName, false, ref args))
             {
                 var method = type.GetMethod(methodName);
                 return Expression.Call(instance, method, args);
             }
 
-            _it = outerIt;
-            _parent = oldParent;
-
             if (!_methodFinder.ContainsMethod(typeof(IEnumerableSignatures), methodName, false, ref args))
             {
                 throw ParseError(errorPos, Res.NoApplicableAggregate, methodName, string.Join(",", args.Select(a => a.Type.Name).ToArray()));