Unskip testTrailingCommaParsing test (#13484)

Author: sobolevn

test-data/unit/check-basic.test

@@ -300,12 +300,15 @@ main:4: error: Argument 1 to "f" of "A" has incompatible type "str"; expected "i
 main:5: error: Incompatible return value type (got "int", expected "str")
 main:6: error: Argument 1 to "f" of "A" has incompatible type "str"; expected "int"
 
-[case testTrailingCommaParsing-skip]
+[case testTrailingCommaParsing]
 x = 1
-x in 1,
-if x in 1, :
-    pass
+x in 1,  # E: Unsupported right operand type for in ("int")
+[builtins fixtures/tuple.pyi]
+
+[case testTrailingCommaInIfParsing]
+if x in 1, : pass
 [out]
+main:1: error: invalid syntax
 
 [case testInitReturnTypeError]
 class C: