bpo:29950: Rename SlotWrapperType to WrapperDescriptorType (GH-926)

diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index 67d3281..3fd66db 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -577,10 +577,10 @@
         self.assertGreater(tuple.__itemsize__, 0)
 
     def test_slot_wrapper_types(self):
-        self.assertIsInstance(object.__init__, types.SlotWrapperType)
-        self.assertIsInstance(object.__str__, types.SlotWrapperType)
-        self.assertIsInstance(object.__lt__, types.SlotWrapperType)
-        self.assertIsInstance(int.__lt__, types.SlotWrapperType)
+        self.assertIsInstance(object.__init__, types.WrapperDescriptorType)
+        self.assertIsInstance(object.__str__, types.WrapperDescriptorType)
+        self.assertIsInstance(object.__lt__, types.WrapperDescriptorType)
+        self.assertIsInstance(int.__lt__, types.WrapperDescriptorType)
 
     def test_method_wrapper_types(self):
         self.assertIsInstance(object().__init__, types.MethodWrapperType)
diff --git a/Lib/types.py b/Lib/types.py
index 1b7859e..929cba2 100644
--- a/Lib/types.py
+++ b/Lib/types.py
@@ -36,7 +36,7 @@
 BuiltinFunctionType = type(len)
 BuiltinMethodType = type([].append)     # Same as BuiltinFunctionType
 
-SlotWrapperType = type(object.__init__)
+WrapperDescriptorType = type(object.__init__)
 MethodWrapperType = type(object().__str__)
 MethodDescriptorType = type(str.join)