test.deepEqual may print incorrect property values for subsequently modified properties SERIOUS ISSUE

test.deepEqual does not examine failing objects immediately, so incorrect values are printed
## Reproduction printout

```
$ nodeunit ../nodejs3/snippets/modules/nodeunit/nodeunit-changedobject.js

nodeunit-changedobject.js
Expected printout: AssertionError: { property: 'object1' } deepEqual { property: 'object2' }
✖ f

AssertionError: { property: 'overwite' } deepEqual { property: 'object2' }
at Object.assertWrapper [as deepEqual] (/usr/local/lib/node_modules/nodeunit/lib/types.js:83:39)
at Object.module.exports.f (/home/foxyboy/Desktop/c505/node/nodejs3/snippets/modules/nodeunit/nodeunit-changedobject.js:13:7)
at Object.wrapTest (/usr/local/lib/node_modules/nodeunit/lib/core.js:235:16)
at wrapTest (/usr/local/lib/node_modules/nodeunit/lib/core.js:235:16)
at Object.exports.runTest (/usr/local/lib/node_modules/nodeunit/lib/core.js:69:9)
at exports.runSuite (/usr/local/lib/node_modules/nodeunit/lib/core.js:117:25)
at _concat (/usr/local/lib/node_modules/nodeunit/deps/async.js:508:13)
at async.forEachSeries.iterate (/usr/local/lib/node_modules/nodeunit/deps/async.js:118:13)
at async.forEachSeries (/usr/local/lib/node_modules/nodeunit/deps/async.js:134:9)
at _concat (/usr/local/lib/node_modules/nodeunit/deps/async.js:507:9)
```
## Reproduction code

``` js
// nodeunit-changedobject.js

module.exports.f = function (test) {

var object1 = {
property: 'object1'
}
var object2 = {
property: 'object2'
}

test.deepEqual(object1, object2)
object1.property = 'overwite'

console.log('Expected printout: AssertionError: { property: \'object1\' } deepEqual { property: \'object2\' }')
test.done()
}
```

从 lib/types.js 中的 test.deepEqual 开始，以堆栈跟踪和 nodeunit-changedobject.js 重现作为入口。运行提供的 nodeunit 示例，并将失败输出与预期打印结果进行比较；当报告的值仍然是调用 deepEqual 时存在的值，而不是之后发生突变后的值时，即表示完成。

由索引模型根据 Issue 内容生成。