Add another little test to make sure we roundtrip multiple list comp ifs ok.

Add tests for generator expressions too.

Lib/test/test_parser.py

@@ -51,6 +51,10 @@ class RoundtripLegalSyntaxTestCase(unittest.TestCase):
         self.check_expr("[1, 2, 3]")
         self.check_expr("[x**3 for x in range(20)]")
         self.check_expr("[x**3 for x in range(20) if x % 3]")
+        self.check_expr("[x**3 for x in range(20) if x % 2 if x % 3]")
+        self.check_expr("list(x**3 for x in range(20))")
+        self.check_expr("list(x**3 for x in range(20) if x % 3)")
+        self.check_expr("list(x**3 for x in range(20) if x % 2 if x % 3)")
         self.check_expr("foo(*args)")
         self.check_expr("foo(*args, **kw)")
         self.check_expr("foo(**kw)")