Inconsistency when try to access an property inside the "with" scope

Hi,
there's an inconsistence when we try to access an property inside the "with" scope.

OS: Ubuntu 16.04 x64
Chakra: 1.10.0.0-beta

Step to reproduce:
```
var o = { f: "foo" };
with (o) {
var desc = Object.getOwnPropertyDescriptor(this, "f");
function f() {
return "bar";
}
if (!(desc.value === undefined)) {
throw new Error('expected: undefined, got: ' + desc.value);
}
}
```
Actual results:
Error: expected: undefined, got: function f() {
return "bar";
}

Expected results:
Pass without failures

V8 and Spidermonkey pass as expected, but Chakra and JavascriptCore returns the function f() inside "with" scope.

Start by running the provided reproduction in ChakraCore on the reported behavior around JavaScript with scopes, then compare the result with V8 and SpiderMonkey as described. Done means the script passes without throwing and the property descriptor value is undefined, matching the expected result.

Written by the indexing model from the issue text.