Possible TypeError in SyntheticUIEvent.js

[vilchik-elena]

With static analysis we have found this issue on the react's code: https://nemo.sonarqube.org/issues/search#issues=AVTMqSKVtu4QdCAX4XJN

On line 29 there is a null check of target but there is no on line 34.

[jimfb]

Eeh, this is really a non-issue. Target is always non-null. I'll submit a PR to remove the null check, since it is a little confusing, but the extra check really wouldn't have hurt anything.