Flow do NOT check expression in JSX attr with namespace

If this is a bug, please try reproducing using https://flow.org/try/.
url: https://flow.org/try/#0PTAEAEDMBsHsHcBQiDGsB2BnALqAhqALygCMA3MgDwCWiooAbgFzWSEDeeAdNABQCUAXzqhWHbnyEiAptEzTxPAYNDAAfIiA

the expression in `v:if` is not checked.

```js
// @flow

const a = 1;

```

```
5:
^ property `l`. Property not found in
8: else={a.l()} />
^ Number
```