PY-20017 Fixed: Unresolved attributes for child class if __new__ is implemented in parent class

For 'self' and 'cls' parameters return containing class as a type

python/testData/completion/ancestorHasDunderNewMethod.after.py

@@ -0,0 +1,9 @@
+class A(object):
+    @staticmethod
+    def __new__(cls, *more):
+        return super(A, cls).__new__(cls, *more)
+
+
+class B(A):
+    def test_method(self):
+        self.test_method()

python/testData/completion/ancestorHasDunderNewMethod.py

@@ -0,0 +1,9 @@
+class A(object):
+    @staticmethod
+    def __new__(cls, *more):
+        return super(A, cls).__new__(cls, *more)
+
+
+class B(A):
+    def test_method(self):
+        self.test_m<caret>