[JSON] implement indentation in the BasicJsonStringifier and expose via API.

test/mjsunit/json.js

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 216 matching lines @@
 TestInvalid('[] ""');
 TestInvalid('[true] ""');
 TestInvalid('{} ""');
 TestInvalid('{"x":true} ""');
 TestInvalid('"Garbage""After string"');
 
 // Stringify
 
 function TestStringify(expected, input) {
   assertEquals(expected, JSON.stringify(input));
-  assertEquals(expected, JSON.stringify(input, null, 0));
+  assertEquals(expected, JSON.stringify(input, (key, value) => value));
+  assertEquals(JSON.stringify(input, null, "="),
+               JSON.stringify(input, (key, value) => value, "="));
 }
 
 TestStringify("true", true);
 TestStringify("false", false);
 TestStringify("null", null);
 TestStringify("false", {toJSON: function () { return false; }});
 TestStringify("4", 4);
 TestStringify('"foo"', "foo");
 TestStringify("null", Infinity);
 TestStringify("null", -Infinity);
@@ skipping 196 matching lines @@
 
 var getCount = 0;
 var callCount = 0;
 var counter = { get toJSON() { getCount++;
                                return function() { callCount++;
                                                    return 42; }; } };
 
 // RegExps are not callable, so they are stringified as objects.
 TestStringify('{}', /regexp/);
 TestStringify('42', counter);
-assertEquals(2, getCount);
-assertEquals(2, callCount);
+assertEquals(4, getCount);
+assertEquals(4, callCount);
 
 var oddball2 = Object(42);
 var oddball3 = Object("foo");
 oddball3.__proto__ = { __proto__: null,
                        toString: "not callable",
                        valueOf: function() { return true; } };
 oddball2.__proto__ = { __proto__: null,
                        toJSON: function () { return oddball3; } }
 TestStringify('"true"', oddball2);
 
@@ skipping 45 matching lines @@
 assertEquals({a: 0, b: 1}, JSON.parse('{"a":0,"b":1}', reviver));
 
 
 // Make sure a failed [[DefineProperty]] doesn't throw
 
 reviver = function(p, v) {
   Object.freeze(this);
   return p === "" ? v : 42;
 }
 assertEquals({a: 0, b: 1}, JSON.parse('{"a":0,"b":1}', reviver));