RegExp.prototype.lastIndex cannot be set properly via Object.defineProperty

## Description

When using the function `RegExp()` to create a RegExp object. The object's `lastIndex` property should be 0 and the property descriptor `writable` should be true. But when i use the function `Object.defineProperty` to redefine the property `lastIndex` . Chakra failed to change its value while all other engines such as V8, SpiderMonkey, and JavascriptCore changed successfully. Is this a normal behavior of Chakra?

## Version

chakra 1.11.22

## Run Command

`chakra-1_11_22/bin/ch testcase.js`

## Testcase

~~~javascript
var regexp5 = new RegExp(/abc/);
print(regexp5.lastIndex);

Object.defineProperty(regexp5, "lastIndex", {
value: "\w?\B",
writable: false
});
print(regexp5.lastIndex);
~~~

## Output

~~~javascript
0
0
~~~

## Expected output

~~~javascript
0
w?B
~~~