Added test cases for pair node key

Author: ckganesan

ast/print_test.go

@@ -57,6 +57,10 @@ func TestPrint(t *testing.T) {
 		{`{}`, `{}`},
 		{`{a: b}`, `{a: b}`},
 		{`{a: b, c: d}`, `{a: b, c: d}`},
+		{`{"a": b, 'c': d}`, `{a: b, c: d}`},
+		{`{"a": b, c: d}`, `{a: b, c: d}`},
+		{`{"a": b, 8: 8}`, `{a: b, "8": 8}`},
+		{`{"9": 9, '8': 8, "foo": d}`, `{"9": 9, "8": 8, foo: d}`},
 		{`[]`, `[]`},
 		{`[a]`, `[a]`},
 		{`[a, b]`, `[a, b]`},