Do not quote JSX attribute keys for IdentifierName (#8045)

Given the following

```js
a = <F new/>
```

We used to generate:

```js
a = React.createElement(F, {"new": true})
```

but now we generate

```js
a = React.createElement(F, {new: true})
```

If you need to quote these (ie for ES3 you can use
transform-property-literals)

packages/babel-plugin-transform-react-inline-elements/test/fixtures/regressions/6276/output.js

@@ -1,3 +1,3 @@
 var test = babelHelpers.jsx(T, {
-  "default": " some string "
+  default: " some string "
 });