Constructing a type with intersection operator causes error if that type is later used in a union

If you use an intersection operator to make a type, and then use that in a union, you can no longer query any properties that may be absent on some of the union members. But if you do not use the intersection operator, and just add in the the property directly, then it works just fine.

```js
// @flow

type A1 = { a:string, data: string }
type B1 = { b:string, data: string }
type X1 = A1 | B1

type Common = { data: string }
type A2 = { a:string } & Common
type B2 = { b:string } & Common
type X2 = A2 | B2

// X1 and X2 should be functionally identical.

function foo1(entry: X1) {
if (entry.a) console.log('foo!') // Works!
}

// Error!
function foo2(entry: X2) {
if (entry.a) console.log('foo!') // Property cannot be accessed on any member of intersection type
}
```

[Try flow link](https://flow.org/try/#0PTAEAEDMBsHsHcBQiSgOqwE4GsDOBCRAFwE8AHAU1AEEBGUAXlAG9QBDALlyMwEsA7AOYAaUABM2RTqG58hoAL7FyVAEL0mrAEZceAkeMnTZ+xcsqgAGhpr0APqHXJUAFQAWvXLfb8xNAEwybrAArtB+bmwAblQUAB5sAMZE0CSgRG5UuGwAtlmRlKJaIUSgmBS4YUReAj6gFJiYWKDwmfygIbgUYgB05lQAwrA5ObDtmoZSHDJ68kqkFtSBE5wmc6AAZKBDI2P9jsssoDprgoqb28Oj-PuWh0ugDqr+zmAYOASIkCH8ybxjoEgsFgtAAFBR+DwSNNrABKFiIUCgXiQUDgyGYEg9NjwxJjXCwaAUHpwQSggDkQNg+HJsMQShQYAAoo0sIRvr8iP92lT-OioTD-PDmIjkaj+Zjsbj8YTiaSKVSaXSFEA)

It shouldn't matter how you construct a type that ends up in a union, right?