test(vm): negative width for center and zfill

Author: dylan-sutton-chavez

compiler/tests/cases/vm.json

@@ -818,6 +818,8 @@
   {"src": "print('-5'.zfill(4))", "output": ["-005"]},
   {"src": "print('abc'.zfill(5))", "output": ["00abc"]},
   {"src": "print('abc'.zfill(2))", "output": ["abc"]},
+  {"src": "print('abc'.center(-1))", "output": ["abc"]},
+  {"src": "print('abc'.zfill(-1))", "output": ["abc"]},
   {"src": "print('hello'[:])", "output": ["hello"]},
   {"src": "print('hello'[1:])", "output": ["ello"]},
   {"src": "print('hello'[:3])", "output": ["hel"]},