[NUI] add null checking for equality operator of ControlState (#2079)
authorYeongJong Lee <cleanlyj@naver.com>
Thu, 29 Oct 2020 05:47:21 +0000 (14:47 +0900)
committerdongsug-song <35130733+dongsug-song@users.noreply.github.com>
Wed, 4 Nov 2020 08:17:17 +0000 (17:17 +0900)
commit48762057fec9f4bacf9e7e33d0094ccc7c701461
treedb96d544e5c377e6e5a99deb13d135548042e919
parente3a10647809895981cccf7d347e112f70c5e7857
[NUI] add null checking for equality operator of ControlState (#2079)

This is patch to prevent a null reference exception in the following
code.

```cs
bool b = null == ControlState.Pressed;
```

Co-authored-by: Jiyun Yang <ji.yang@samsung.com>
src/Tizen.NUI/src/public/BaseComponents/ControlState.cs